30,000 Japanese gamers become trapped in the fantasy online game world Elder Tale. What was once a sword-and-sorcery world is now the real world. Shiroe attempts to survive with his old friend Naotsugu and the beautiful assassin Akatsuki.
In medias res Shiroe, Naotsugu and Akatsuki find themselves ambushed by a pack of briar weasel monsters. Following a game update in the present, a confused Shiroe awakens to find himself in the District of Akihabara inside the Elder Tale MMORPG while donning his in-game avatar. He encounters other panicked players and all find themselves unable to log-out. Accessing his HUD, Shiroe quickly makes contact and teams up with his friend Naotsugu. Eventually the assassin Akatsuki joins them on account of helping her revert to a feminine avatar. The next day, Shiroe and co. meet with his friend, the Master of the Crescent Moon Alliance Guild—Marielle to compare notes on their current reality. Shiroe and co. learn that the teleportation gates across all the Japanese game districts have been rendered offline in addition to the start of a widespread guild recruitment campaign to deal with the changes of the recent "Novasphere Pioneers" update. After declining Marielle's recruitment offer, Shiroe and co. discuss the possible outcomes of an in-game death and head into the Archive Tower Forests to test the theory where they are ambushed by the pack of Briar Weasels. After some initial difficulty, they are able to overcome the ambush by naturally moving their bodies to attack rather than relying on their preset attack commands. Elsewhere, a girl called Serara makes a panicked call to Marielle while being chased by two male players as a mysterious figure looks on.
Upon dying while fighting monsters, a player revives at the Cathedral and Shiroe deduces that they are truly trapped inside the game. After another meeting with the Crescent Moon Alliance, Shiroe and co. learn of the stabilizing power balance between guilds in the District of Akihibara in addition to a rise in recent PKings. While heading back to Akihibara after a day of training Shiroe and Naotsugu anticipate an ambush from nearby PKers, forcing them into a direct confrontation. However the PKers' overconfidence quickly becomes their undoing as Shiroe and Naotsugu's team work proves to be too much for them and are quickly overpowered by the latter's high-level combinations. In desperation, the PK leader tries calling in reinforcements only to discover they have been already taken down by Akatsuki. Feigning defeat, the leader tries to attack Shiroe however Akatsuki kills him. In the aftermath, Shiroe and co. try to discern the motives of the players in the game, and he deduces that since people can survive in-game without doing anything, the string of PKings were purely for entertainment purposes. Afterwards, Shiroe receives a call from Marielle and learns that she intends to take a party on a mission to rescue their comrade Serara in the District of Susukino and asks Shiroe to take care of the guild in her absence. However, Shiroe and his friends counter by deciding to go in Marielle's stead.
While continuing on their way to the District of Susukino, Shiroe, Naotsugu and Akatsuki enter a familiar dungeon known as the Depths of Palm. As Marielle calls to check up on their progress, Shiroe surprises her at the distance they managed to cover in three days. Meanwhile in Susukino, Serara seems to be doing fine in the care of Nyanta—a player using a cat avatar who had saved her from her pursuers. While they wonder about the kind of people Shiroe and co. are, the Dark Guild, Brigandia continue looting and pillaging the district. Back in Akihabara, Marielle begins a meeting with the guild masters of Akihibara, while another mysterious guild master learns of the meeting and of Shiroe's movements. Meanwhile, Shiroe and co. cross an ancient bridge in the dungeon which suddenly starts crumbling and causes Shiroe to plummet into the lake below. As Shiroe recalls his time with the adventuring group, Debauchery Tea Party, he regains consciousness to find himself having been saved by his comrades. Eventually Shiroe and co. find themselves face to face with the dungeon's boss, a Novasphere Pioneers' creature called the Rat-maso and quickly engage and defeat it battle. Afterwards, they finally arrive at the dungeon's exit and are rewarded with a spectacular view of the sunset over the channel. Elsewhere, the guild master of Brigandia—Demikas, issues a manhunt for Serara and Nyanta.
Finally arriving in Susukino, Shiroe, Naotsugu and Akatsuki enter the district weary of an ambush by the Brigandia Guild. Meanwhile, as Demikas becomes alerted of their arrival, Shiroe meets up with Serara and Nyanta at a secret location, and shockingly discovers that his old friend Nyanta had been the one protecting Serara. Afterwards, Shiroe relays his plans with Naotsugu and Akatsuki and prepares to leave the district with Nyanta and Serara. After having waited patiently for them to exit the district, Shiroe, Nyanta and Serara are surrounded by the Brigandia guild and Shiroe taunts Demikas into a duel with Nyanta. As Nyanta's swashbuckler class inflicts severe status ailments on Demikas, he crudely calls in his guild members for aid however Naotsugu intercepts them with Anchor Howl. Eventually, Naotsugu and Nyanta's HP drops to dangerous levels and Shiroe has Serara heal them. With the healing having seemingly little effect, Naotsugu activates Castle of Stone and buys them enough delay time for Shiroe to ensnare Demikas in Thorn Bind Hostage, allowing Nyanta to defeat him. As Akatsuki marvels at their perfect timing and silent teamwork while taking down Demikas' remaining healers, Serara delivers the finishing blow to Demikas in defense of Shiroe, winning the battle. With their mission successful, Shiroe, Naotsugu and Nyanta summon three griffons and the party makes their way back to Akihibara.
Having flown far out of Brigandia's reach, the group breathes a sigh of relief and Serara can't help but be overwhelmed at the kindness Shiroe and co. showed in her rescue. The party then sets up camp and Nyanta brandishes his cooking prowess by explaining that only those with the Chef sub-class are able to manually prepare food with flavor. After a venison barbeque supper, Nyanta, Shiroe and Naotsugu explain their history as part of the legendary adventuring group—Debauchery Tea Party, which causes Akatsuki to lament her own abilities. As their journey back to Akihibara continues, Shiroe reminisces about his time spent mentoring two beginners—Tōya and Minori, just before the Apocalypse, and recalls having glimpsed them joining a guild back in Akihibara. The next day, a sudden thunderstorm forces the party to seek shelter in a nearby farming village and they meet Fedor—one of the People of the Land. After interacting with Fedor and his grandchildren, Shiroe deduces that the NPCs of this world have more human characteristics, and making themselves—the anomalies of the world. Elsewhere, Tōya and Minori along with other beginners find themselves taken advantage of by the guild who coaxed them into joining. Finally, as Tōya and the rest of his guild set out the next day, he happily notices Shiroe and co. safely back in Akihibara, but finds himself unable to meet him.
The Crescent Moon Alliance guild throws a party in their guild hall to commemorate Serara's return, in addition to keeping Nyanta's cooking methods a secret from the rest of the city. Afterwards Marielle explains to Shiroe that during his absence, Akihabara remained relatively peaceful despite an unnatural uneasiness befalling its citizens whereby no fault of their own, a social divide was established between the strong and weak guilds. Marielle also outlines that since the player level-limit was raised to 100 following the Novasphere Pioneers update, the stronger guilds such as the Black Sword Knights and Silver Sword have been leveling up using EXP pot items obtained from the Hamelin guild who had been requiting low-level players for the sole purpose of creating a monopoly on their EXP pots to the stronger guilds. Following this news, Shiroe later ponders on all of his excuses up until that point but upon running into Nyanta, realizes that he had just been using them as a means to run away from the reality of Akihabara's state of affairs—despite his friends remaining by his side. Afterwards, Shiroe calls Minori and assures her that he will save them. Filled with new resolve, Shiroe meets with Marielle, Henrietta and Shōryū the next day and asks them to aid him and his newfound guild—Log Horizon, in ending Hamelin's plot and restoring Akihabara's sense of goodwill.
Naotsugu, Shōryū and Hien begin hunting ingredient monsters in the Imperial Garden Forest while the girls, builders and cooks of the of the Crescent Moon Alliance along with Nyanta begin preparing themselves for one of Shiroe's plans. At the same time Henrietta and Shiroe task Marielle with approving an exorbitant amount of budget requests for the guild as part of Shiroe's plan to obtain his requested five million gold funding by taking advantage of the fact that the world of Elder Tale has no strict ruling on how currency should be obtained. The following day the Crescent Moon Alliance opens a food booth in the city and despite initial reluctance from the citizens, becomes an instant hit with word of their delicious food quickly spreading throughout the city. Afterwards, the stall manages to make over forty thousand gold in profit despite their sales being restricted by the total amount of citizens living in Akihabara in addition to the total number they can serve daily. Shiroe then leaves the next stage of his plan to Henrietta before he informs Minori of their progress and urges her to wait a while longer. That night, Shiroe and Nyanta meet with Soujirou Theta—master of the Caravan of the West Wind guild and former Debauchery Tea Party member and asks for his aid, which he gives to Shiroe without hesitation. Finally Shiroe beings the second stage of his plan the next day.
Following the second stage of Shiroe's plan, Marielle and Henrietta meet with Karashin—master of the Shopping Street 8 guild to discuss an agreement involving the exchange of food ingredients. Karashin tries being coy in his attempt to establish an exclusive deal with the Crescent Moon Alliance's food business. Having already anticipated this, Shiroe has Marielle and Henrietta introduce their intention of bringing in the masters of the other business venturing guilds—Michitaka and Roderic of the Marine Agency and Roderic Merchant Guild respectively—thus forcing Karashin to hurriedly accept the Alliance's proposition at a severely reduced price. Meanwhile, Minori laments all of the struggles she and Tohya faced when they became trapped within Elder Tale and that they didn't heed Shiroe's advice before it was too late, thus making them unworthy of Shiroe's rescue. Back at the meeting, Shiroe has Henrietta play a dangerous game of baiting the three guild masters into investing the remaining amount of gold under the false pretense of an extremely profitable legendary Novasphere Pioneers quest led by non other than the "Villain in Glasses" himself—Shiroe. Afterwards, Tohya relates the same feelings of undeserved rescue to Minori before the Crescent Moon Alliance and Log Horizon issue invitations to Akihibara's largest guilds for a conference to discuss the city's future.
The Round Table Conference begins as the masters of Akihibara's most influential guilds gather at the city's Guild Hall. Shiroe firstly eases that he seeks only to improve the city's living state, prompting disinterest and departure from Silver Sword's guild master—William Massachusetts. Unperturbed, Shiroe continues his explanation of the conference's formation. Elsewhere, as the Hamelin captives prepare to escape, Shiroe mentions the EXP Pot extortion campaign including Susukino's dire state with Black Sword Knights' guild master—Issac arguing the lack of laws in the world. D.D.D.'s guild master—Crusty asks of a guild's fate should they refuse the laws to which Shiroe proposes harsh sanctioning. However, Honesty's guild master—Ein along with Issac and Crusty argue of the agreement's flaw should they refuse to cooperate, with Issac even threatening war. Shiroe then plays his trump card, revealing his acquisition of the Guild Hall using the five million gold and counter blackmailing the guilds over his absolute control of their affairs. Meanwhile, as the Hamelin captives manage to escape the Hall, Minori and Tohya are unfortunately captured by Hamelin's master—Schrieder. However Shiroe's control of the Hall along with help from his friends manage to successfully blacklist all of Hamelin's members. Finally, as Shiroe makes one last pitch to the conference, Issac demands Shiroe's plan.
As the Conference continues Marielle reveals the secret behind preparing food with flavor followed by Michitaka's news of the collaborative invention of a steam engine. Shiroe then explains that by simply using one's own hands instead of the command menu, new things can be invented which in turn would start a supply and demand chain reaction and hence drive Akihibara's economic system. Shiroe then proposes the establishment of Human Rights laws that would ban the PKing, kidnapping and imprisonment of players and also allow them the freedom to join and leave guilds as they desire—further suggesting that these laws also apply to the People of the Land much to the conference's surprise. However, with Marielle's help, Shiroe convinces the conference of the People's importance and the dire need to coexist peacefully with them. Presented with an undeniable case, the guild masters unanimously decide on the Round Table Conference's formation and move on to inform the city and mark the occasion with a celebration. A week later, Shiroe secures a headquarters for Log Horizon and welcomes Tohya and Minori while at the same time, outside spies begin to infiltrate Akihabara. Elsewhere, the spies report back to Sergiatte of the League of Freedom Towns – Eastal district before being approached by a woman called Lady Lenessia.
While hunting, two People of the Land notice a strange phenomenon over the forest. Meanwhile. with Akihibara now bustling with activity, Naotsugu and Akatsuki take Tohya and Minori under their wing for training. As Shiroe also starts experimenting with his scribe subclass, Marielle starts craving to visit the beach. This gives Shiroe the idea too hold a summer training camp for new players. Afterwards, emissaries of Eastal arrive in Akihabara and invite the Round Table to a meeting and ball. Having already anticipated this, Shiroe informs Crusty that it would be a prime opportunity to learn more about the People of the Land and along with Michitaka, Henrietta, Akatsuki and Misa Takayama set off the following month. At the same time, the training camp also set off to Choushi where they end up having fun at the beach. Marielle and Minori also speak to People of the Land as part of Shiroe's suggestion that they learn as much as they can. Elsewhere, the Round Table representatives arrive at The Palace of Eternal Ice and meet with Sergiatte during the ball. As Crusty and Sergiatte begin a discussion Shiroe notes that both the adventurers and the People of the Land are weary of the other. Finally, as Princess Lenessia graces the dance with her presence, Naotsugu informs the trainees that they will head into the Forest of Lagranda dungeon for party training the next day.
As the ball continues, Sergiatte invites the Round Table representatives to participate in the dance due to the People of the Lands' expectation. However much to the group's reluctance, Crusty nominates Shiroe to participate and with help from Henrietta's bard subclass, they quickly impress the entire ball. Afterwards, Minori calls Shiroe to inform him of their dungeon training and he reminds her of his teachings. The next day, Shiroe explains that the People of the Land would compete with themselves over dealings with the Adventurers in order to obtain their fighting and technological power by putting them in the People's debt. He then proposes that they create rules to protect the Round Table when the People inevitably start approaching their guilds individually and hence has Akatsuki begin reconnaissance as preparation. Elsewhere, the training camp makes their way to the Forest of Lagranda and split up into groups, however Minori has trouble speaking her mind in a group with Tohya, Rundel Haus Code, Isuzu and Serara. Eventually the group encounters some Skeleton monsters and familiarize themselves with their teamwork. Despite their best attempts however, they are quickly overpowered by the next wave of monsters and make a tactical retreat. Back at Palace of Eternal Ice, Crusty introduces himself to Lenessia.
The Round Table Representatives find themselves with invitations to various meetings throughout the palace and they divide them amongst themselves. Shiroe will attent a dinner meeting with Count Kirino of Tsukuba and the Academic's Guild, Krusty will go to an evening party of young knights and Michitaka will attend a banquet with Lord Darte.
Meanwhile, as Elissa warns Lenessia to be weary of the Adventurers, the latter recalls her previous meeting with Krusty where he uses her as a convenient shield against scrutiny from the palace folk. The next day, Lenessia witnesses the sparring session with the palace knights where Krusty craftily manipulates her into accompanying him to the evening party as a reward for defeating all the knights. Elsewhere, Akatsuki eavesdrops on two noblemen at the palace and learns of a group called the Knights of Izumo, who have apparently dissapeared. Afterwards, Krusty explains to Lenessia the freedom of the Adventurers due to their resolve as opposed to her sheltered life.
Meanwhile, Touya's Party is seen fleeing from a group of Skeletons. When they've gotten away from them, Rundelhaus Cord starts complaining that even though they are at a higher level they can't seem to defeat the Skeletons. Minori tries to speak her mind, but quickly backs down again.
At the beach Marielle and Shoryu notice a strange phenomenon on the ocean horizon.
Back at the Ancient Palace of Eternal Ice, Lord Darte asks Michitaka to share sea faring technology with him. After Krusty and Lenessia attend the formal party, Krusty explains his interest in Lenessia by comparing her to his sister in the real world. Elsewhere, Shiroe meets with Akatsuki after his meeting with the Academic's Guild and learns of the information she gathered, when suddenly a weird phenomenon happens: everything start to vibrate and the flowers wither as the Enchanter and Assassin readied their weapons. Then suddenly a mysterious man appears, introducing himself as Ri Gan the mage from Miral Lake.
Being an academic in the study of World-class magic, Regan offers Shiroe and Akatsuki an explanation of the World Fraction spell and its thrice use in the world's history, with Shiroe correctly deducing the third time being the Apocalypse. Regan explains that 350 years ago the Human, Elf and Dwarf races destroyed the Alv kingdom out of technological jealousy. Seeking revenge, the remaining Alves cast the first World Fraction which resulted in the creation of the endlessly respawning demi-humans which pushed the planet into a world war. This caused humanity to create powerful hybrid races to aid in the war, until they were forced to cast the second World Fraction which summoned the Adventurers to their aid, some 240 years ago. As Regan also explains that Shiroe's name appeared in the world's history some 98 years ago, Shiroe confirms the events using the game's rate of time as it correlates to the real world, including the start of the open beta which brought the human-controlled Adventurers and when he began playing Elder Tale. Regan then moves on to explain his Spirit Theory which involves how revival works and that memories in the form of XP are lost during the process—a theory which Shiroe decides to withhold from the Round Table for the time being. Meanwhile, Minori finally decides to speak her mind to the training group.
Minori suggests that their group hold off on entering the dungeon until that afternoon much to the protest of Rundelhaus, and instead has them each explain their respective skills. In doing so, the group discover that their teamwork lacked cohesion. After Minori explains the basics of party combat as taught to her by Shiroe, the group enters the dungeon the next day. Armed with their new knowledge, each person assumes a clearly defined role in the party and they finally overcome the battles they were forced to retreat from previously. Back at the Palace of Eternal Ice, Shiroe starts documenting all the information he learnt from Regan and lies to Henrietta to keep her from discovering them. While pondering on what to do next, Shiroe receives a call from Minori where she gives him the progress of their training and thrilling him with the fact that Minori's group finally realized the importance of teamwork and friendship. The next day, Crusty continues to meet with Lenessia while Minori, Serara and Isuzu discuss the latter's compatibility with Rundelhaus. However that night, as Rundelhaus and Isuzu have another exchange, the latter discovers that the system strangely prevents her from adding Rundelhaus to her friend list. The next day, the training camp at the beach find themselves in a sudden attack by a massive army of Sahuagin monsters.
The camp begins encountering goblins inland while Nyanta discovers a massive goblin army approaching from the north. After pooling their knowledge, Naotsugu informs Shiroe who organizes an emergency relay conference with the Round Table. Shiroe postulates that the recent attacks are part of a quest known as "Goblin King's Return". The Adventurers then realize that they neglected quests from the People to defeat the goblins in their development of Akihabara which in turn caused the Goblin King to unite a great army. At the same time, Lenessia's father leaves to defend the town of Maihama from a goblin invasion. Afterwards, the training camp discovers a goblin raiding force marching towards the nearby town of Choushi. Meanwhile Shiroe summons Soujirou and the West Wind Brigade to the Palace of Eternal Ice to aid in its defense should it come under attack. Shiroe then informs the Round Table Representatives of his hypothesis that an in-game death induces memory loss, which Crusty verifies and shockingly reveals that he had already lost some memories of the real world. Elsewhere, the training camp makes their way to the Choushi town but they end up arriving too late. However, Minori decides that the Adventurers shouldn't wait for the People to ask for their aid, and instead, attack the goblins themselves.
Minori manages to convince Naotsugu and Nyanta to let her party begin a surprise attack against the goblin forces. Meanwhile, the Eastal Lords hold their own private conference to discuss Yamato's current predicament, including the Izumo Knight's disappearance and of sacrificing Lord Kiliva's Tsukuba City to the goblins as a possible battle strategy. Lenessia eventually overhears this information as well as the Lords' intention to use the adventurers. In the meantime, Shiroe prepares specific roles with Crusty and Michitaka for their talks with the Eastal Lords until they are finally summoned. Having predicted that the Lords would try to gather more information from them, Shiroe uses the same tactic, prompting an outburst from Kiliva stating that the adventurers have a responsibility to act. Although Michitaka violently retorts that they deserve more respect than what the League has shown them. At this time, Lenessia reluctantly makes a sudden appearance and notes the League's error in negotiating with the adventurers and instead proposes that she go to Akihabara to respectfully recruit volunteers to aid the People. Afterwards, as Minori's party continue fighting with their own resolve, Shiroe, Akatsuki, Crusty and Lenessia make their way to Akihabara as Shiroe remarks that Lenessia may be the one to change the Cities of Eastal.
Upon arriving in Akihabara, Lenessia can't help but marvel at the different culture of the city. Shiroe and Crusty organize a meeting in the middle of the city, drawing hundreds of adventurers. Wasting no time, Shiroe stirs the crowds with the threat the goblin army poses to the League of Freedom Cities, Eastal. After presenting the option that the adventurers do not have to act, Shiroe introduces Lenessia who makes a heartfelt plea for adventurers to aid her in defending Eastal. Heeding Lenessia's words, the adventurers rally behind her with Crusty and Shiroe issuing the expedition to defeat the goblins as a quest from the Round Table. Crusty then takes almost half of the adventurers, along with Lenessia to the Narashino Port while Shiroe heads to the Midraunt Equestrian Park to set up a battle headquarters. In the meantime, Sergiatte meets with Michitaka and Henrietta to explain the developing rift between the League and the Cowen family thanks to Lenessia's actions and of the power difference between the People and the adventurers, although they decide to wait for a solution from Shiroe. Elsewhere, as Lenessia ponders on the consequences of her actions, the training group makes a stand against the goblins at Choushi. Finally, after Crusty and Misa Takayama divide the adventurers into raiding parties, Crusty issues them the single order to kill all goblins.
Upon arriving on the battlefield, Crusty's group engages the goblin army in battle at the Kasumi Lake. Meanwhile, at the headquarters established at the Midraunt Equestrian Park, Shiroe explains the pivotal role the town of Choushi plays in his plan to contain the goblin advancement. At the same time, a large army of Sahuagin monsters begin moving towards Choushi and the trainees persuade Marielle to let them defend the town. While watching the trainees fight, Naotsugu and Nyanta comment on their battle styles and of Minori's attempt to imitate Shiroe's Full-Control Encounter tactic. As the battle of Choushi wears on, Minori's group takes off to defend other parts of the town while Shiroe informs Marielle of the arrival of reinforcements in another hour. With the battle taking a huge toll on them, Minori's group soon finds themselves slowly overpowered against a small group of goblins and dire wolves. As Tohya's HP reaches critical levels, Minori starts losing control of the battle. However Rundelhaus suddenly charges at the last two wolves with his magical gauntlets and kills them in a suicide attack. In the aftermath, Rundelhaus' friends try in vain to heal and revive him. Already knowing the inevitable though, Isuzu tearfully explains Rundelhaus' nature as a Person of the Land—who dies permanently. Refusing to give up, Minori immediately asks Shiroe for his aid.
Shiroe leaves for Choushi while Minori relays their situation. Using Regan's theories of revival, Shiroe has Minori, Serara and Isuzu alternate between restoring Rundelhaus' health and magic to prevent his body from being destroyed. Meanwhile, Misa and Lenessia update Crusty on the status of the battle and they prepare to intercept the goblin general's forces in Zantleaf. At the same time, Shiroe arrives at Minori and co's location and uses his enchanter abilities and a revival item to restore Roundelhaus' magic and temporarily revive him as a zombie for a few minutes. As Rundelhaus awakens and accepts his fate much to the grief of his friends, Shiroe sharply rebuffs his resolve. Using the theory to bend the laws of the world by making things oneself, Shiroe presents Rundelhaus with a contract to join Log Horizon as an adventurer. Willing to use his abilities for the good of others, Rundelhaus signs the contract and dies as one of the People of the Land. Elsewhere, Crusty and the other adventurers mercilessly slaughter the goblin general and his forces at Zantleaf while Marielle's group and the reinforcements repel the Sahuagin monsters invading Choushi. Afterwards Shiroe explains his definition of an adventurer to Minori. Finally, Rundelhaus awakens at the cathedral to his new status as an adventurer and gets a severe scolding from Isuzu for his recklessness.
A month following the battle at Zantleaf, Eastal holds a grand ball for the adventurers for their victory against the goblin general, which Shiroe includes in his plan to eventually defeat the Goblin King in Seventh Fall. At the same time, Shiroe does his best to avoid attending the ball and learns of an event called the Demon Festival of Suzaku Gate which occurred in the west of Yamato. While walking the Palace of Eternal Ice, Shiroe surprisingly listens to a mysterious woman cryptically telling a group of children the story of how he saved Rundelhaus. Afterwards Shiroe visits Regan and learns that another adventurer in the district of Minami had also used world-class magic along with the knowledge that the Izumo Knights were involved in the Demon Festival. Back at the ball, while Crusty and Lenessia dance, the latter recalls a conversation with Sergiatte where he assigns her as the Eastal ambassador to Akihabara in order to repay the adventurers. At the same time Shiroe thanks Akatsuki for her help in their previous trials with a dance. Sometime later, Lenessia moves to Akihabara to begin her ambassadorial duties and Shiroe spreads the information of the consequences of death as a rumor to suppress panic. As things return to normal in Akihabara, Marielle proposes that they hold a festival to celebrate the autumn season.
The city of Akihabara becomes much more lively than usual as the Scale Festival looms over the horizon. While detached from the city's activities, Shiroe continues his work until Henrietta suggests that he take time away to enjoy the festival with everyone. Afterwards both Minori and Akatsuki attempt to invite Shiroe to the festival's couple cake-eating contest. Minori explains to Isuzu that she intends to use the contest's reward to improve the public's trust of Shiroe which had been wavering as of late. The next day, Shiroe participates with both Akatsuki and Minori and the former receives a large amount of envy from the other participants for bringing two girls, which only escalates when Akatsuki and Minori begin competing with each other for his attention. However the trio end up failing the contest and while mulling over the day's events atop Log Horizon's headquarters, Shiroe decides to better spend his time with his guildmates. Akatsuki then joins him and they have an awkwardly brief conversation where she shows her feelings for him despite Shiroe's obliviousness. At the same time, Minori catches them and runs away with a broken heart after admitting her feelings for Shiroe to herself. However with encouragement from Tohya, Minori realizes that since she has yet to do anything about her feelings, she has no reason to be sad.
The second day of the Scale Festival gets underway and the members of Log Horizon go off on their own for the day's activities. Meanwhile, Minori stops off at Karashin's busy office to procure tickets for the Twilight Banquet and offers her services while the city's inhabitants begin getting into squabbles with merchants of the People of the Land. At the same time Minori begins to use her apprentice sub-class to help Karashin account for the festival's finances. Elsewhere Nyanta peacefully kicks a rowdy Person of the Land out of a restaurant and reports the matter to Shiroe. While the Black Sword Knights and D.D.D. guilds work on maintaining order during the festival, they resolve more disputes involving the People of the Land. Issac and Crusty then discuss Shiroe's traits and agree that he works his best when for the good of others. After putting a stop to yet another rowdy Person of the Land, Shiroe finally notices the strangeness of the People's behavior and after Minori reports inconsistencies in the festival's paperwork all resulting from errors by the People, Shiroe confirms that the city may be under attack and makes haste for the Guild Building while disgruntled at his own carelessness. Meanwhile, a vessel called the New Spirit Ship led by the sinister looking Lord Malves prepares to make contact with Akihabara.
Shiroe postulates that the People of the Land led by the newly arrived Lord Malves of Westelande to be responsible for the attack on the city, with the intention of destroying the Round Table's reputation and treaty with Eastal. In preparation to counterattack, Shiroe has his comrades provide him with more information while Minori does her best to keep Karashin's office flowing using the skills taught to her by Shiroe. Afterwards Shiroe begins plotting all the points of disturbances caused by the People of the Land but has difficulty in discerning a pattern out of their randomness until it finally dawns on him that the People are improvising on the spot. While stressed for a solution Shiroe gets a spark of genius after meeting Soujirou who had innocently beaten the cake contest with the help of his guild. In the meantime Lord Malves crashes the Twilight Banquet and corners Lenessia over his supposed mishandled cargo documents. Elsewhere, in a brilliant countermeasure, Shiroe uses the West Wind Brigade's infatuation with Soujirou as incentive for them to patrol the city and handle the disturbances. Shiroe and co. then learn of the banquet disturbance and decide to make the festival as enjoyable as possible with a fireworks display as their true counterattack. Finally, Shiroe makes an appearance at Lenessia's banquet.
Shiroe, accompanied by Crusty and Michitaka arrive at the banquet and easily counters Lord Malves' ruse with one of their own, forcing the latter to make a hasty retreat. Shiroe then excludes himself from the continuing festivities until Minori voices her concern over his actions. However Shiroe reassures her that he accepts appearing as the villain as long as he can accomplish his tasks, something which also Akatsuki berates herself for being blind to. Sometime later, Shiroe goes to meet with the contact he sent to Minami—Ōshima, although a disguised woman calling herself Dariella confronts him instead. Upon seeing through her disguise though, Shiroe forces the leader of Minami's lone guild—Nureha of Plant Hwyaden to reveal herself. Afterwards, each reveals the information they possess on the other's accomplishments, with Nureha also voicing her intention to recruit Shiroe because of a supposed past meeting of theirs. She then explains her knowledge of his research into finding a way back to the real world and bribes him with her resources and his ambivalence towards Akihibara. However Shiroe rejects Nureha's proposal, forcing her to withdraw, still with her goal to have him. Later, the Scale Festival enters its last stages and Log Horizon sits down to dinner and reassures Shiroe of their intention to help him however they can. Faced with new challenges, Shiroe issues Log Horizon their next goal of changing the world of Elder Tale.
In the epilogue, Shiroe notifies Regan of his intention to leave Akihibara and Regan asks to accompany him.