The Agent of the Shinigami arc is the first season of the Bleach anime series. The episodes are directed by Noriyuki Abe and produced by TV Tokyo, Dentsu, and Studio Pierrot. In the English release by Viz Media, its title is translated as The Substitute. The episodes are based on Tite Kubo's Bleach manga series, spanning twenty episodes. The episodes' plot covers the adventures of Ichigo Kurosaki after becoming a Soul Reaper and assuming the duties of Soul Reaper Rukia Kuchiki. The arc initially ran from October 2004 until February 2005 in Japan on TV Tokyo. The first English airing of the series was from September 2006 until January 2007. It was shown on both YTV's Bionix and Cartoon Network's Adult Swim programming blocks, with Bionix airing the show one day sooner. The arc started airing in the UK starting in September 2007 on AnimeCentral. The episodes use three pieces of theme music: one opening theme and two ending themes. The opening theme is Orange Range's single "Asterisk". The ending theme for the first thirteen episodes is "Life is Like a Boat" by Rie Fu, while the remaining seven used "Thank You!!" by Home Made Kazoku. The arc was released on five DVD compilations, each containing four episodes of the show. They were released in Japan from February 2, 2005 to June 1, 2005. Viz Media's release of the DVDs was made from November 5, 2007 to July 31, 2007. The first of these compilations, with art featuring the series main character Ichigo Kurosaki, was nominated at the American Anime Awards in 2007 for best DVD package design. A DVD collection box, containing all twenty episodes of the arc, was released by Viz Media on October 30, 2007. Manga Entertainment released two DVDs containing the first season in the United Kingdom on November 5, 2007 and March 3, 2008. A compilation of these two volumes was released on May 5, 2008.
Ichigo Kurosaki, a teenage boy who can see ghosts, helps a young girl ghost when some skateboarders knock over a vase offering for her. The next day Ichigo sees the young girl being chased by a big monster called a Hollow. Ichigo goes to help the girl but when the girl is just about to be eaten, a female Soul Reaper, Rukia Kuchiki, appears and saves them. That night Rukia visits Ichigo’s room and is surprised when she realizes she is visible to him. While they are conversing a Hollow appears and terorizes Ichigo’s family and household. After receiving a terrible injury from the Hollow, Rukia makes a final attempt to save her life, as well as that of the Kurosaki family and transfers her powers to Ichigo so he can save his family.
After the previous night's attack, Ichigo decides to check up on his family and finds that they do not remember anything that happened. In school, Ichigo meets the Soul Reaper from the night before, Rukia Kuchiki; she is posing as an exchange student until her powers return. Rukia tells Ichigo that he must take her place as a Soul Reaper for now. Later when attacking a Hollow, Ichigo recognizes the Hollow as Orihime Inoue’s older brother.
Orihime and her friend Tasuki are being attacked by a Hollow who was once Orihime's brother. Ichigo shows up and begins fighting with him. Orihime's brother is also struggling to gain control. Orihime is almost killed but her soul remains attached to her chain. Finally Orihime's brother gains control long enough to say one last goodbye to his sister before Ichigo sends his soul off to the Soul Society.
Ichigo’s friend Chad finds a bird that is rumored to bring bad luck. Chad takes the bird in anyway because he has a soft spot for animals. Ichigo’s sister Karin finds out that the bird is really the soul of a young boy whose mother was killed. The boy is now being hunted by a Hollow. Karin makes Ichigo promise that he will save the boy.
Rukia and Chad are fighting the Hollow who was hunting the young boy's soul. Chad cannot see the Hollow but he can sense it and attacks it. Rukia can see the Hollow, but since she still has none of her Soul Reaper powers her attacks have no effect. A little while into the fight Ichigo appears and starts fighting the Hollow. When Ichigo defeats this Hollow it is sent to Hell and not the Soul Society because the soul slayer can only cleanse sins after death not ones during life.
Rukia purchases a temporary soul at Urahara’s store for Ichigo to use when she is not around and he needs to fight a Hollow. What Rukia does not realize is that what she purchased isn’t a normal temporary soul; it is a modified soul with special powers created by the Soul Society. When this modified soul takes Ichigo’s place it decides to have a little fun in Ichigo’s body and refuses to give it back to Ichigo.
While Ichigo is fighting with the modified soul Rukia gets a message on her spirit phone about a nearby Hollow. Ichigo and the mod soul then defeat the Hollow together. Shortly after this happens Urahara removes the mod soul from Ichigo’s body. Instead of getting the mod soul destroyed Ichigo places it in a stuffed animal and gives it the name Kon.
On the anniversary of his mother’s death Ichigo and his family visit her grave. While he is there Ichigo remembers the day his mother died. Rukia is found by a Shinigami who asks her why she hasn’t returned to the soul society. Ichigo accidentally tells him that he is her substitute Shinigami; which happens to be a felony. Meanwhile Ichigo’s sisters are being attacked by a Hollow.
Ichigo finds out that the Hollow attacking his sisters is the same Hollow that killed his mother 5 years earlier. This Hollow is called the Grandfisher and has evaded the Shinigami for over 50 years. Because of the fact that this Hollow killed his mother to defend his pride Ichigo must fight it alone.
Don Kan’onji, the star of a show that specializes in spirit exorcism, comes to Ichigo’s town to do a live show. Kan’onji thinks he is exorcising an earth bound spirit but instead he turns it in to a Hollow. Now he must rely on Ichigo help to defeat it.
Rukia gets a message on her pager about a nearby Hollow. When Rukia and Ichigo arrive at the place the where Hollow was supposed to be they find out that it had already been defeated. This happens once again but this time shortly afterwards a man who calls himself a Qunicy confronts them. Rukia goes to the Urahara shop to learn more about what a Qunicy is. She learns that a Qunicy is a person that kills Hollows. But the way a Qunicy defeats a Hollow is different; they totally destroy a Hollow while a Shinigami only "cleanses" its soul.
Uuryu and Ichigo have a contest to see who can destroy the most Hollows after Uuryu releases his Hollow bait. Meanwhile Chad is being pursued by a Hollow because he has spiritual powers. He runs into Ichigo’s sister Karen and must protect her and her friends from the Hollow with his powerful right arm.
Orihime and her friends are being attacked by a hollow who can shoot seeds that control people from its head. Orihime realizes that she has a spiritual power where she can control six small fairy like beings. She uses this power to defeat the hollow. Later Orihime and Chad are taken to Urahara Kisuke's store where they are told about Shinigami and Hollows. Meanwhile Uuryu is starting to believe that something larger is going on because his Hollow bait shouldn't have attracted so many Hollows.
Rukia tells Ichigo why the Shinigami defeated the Quincy 200 years earlier. Ichigo confronts Uuryu with this knowledge while they are fighting the Hollows. This makes Uuryu remember how his Sensei died. While reminiscing Ichigo and Uuryu notice they are surrounded by Hollows and must work together to defeat them. While they are fighting Urahara and his friends show up and defeat the Hollows. Now Ichigo and Uuryu can concentrate on the Menos, a gigantic Hollow formed from hundreds of Hollows, which just appeared in the sky.
Kon's on a mission. And this mission involves getting love from the ladies. Too bad for this stuffed lion, as everything he hopes for gets flipped upside down and around. Also, Urahara gets a strange visit from an even stranger black cat. One that knows him well enough to see through his faux attitude.
The feelings Rukia have been experiencing of late drive her to run away. But she doesn't get far, as two familiar Shinigami come forth to claim her. Lucky for her the Quincy, Ishida Uryuu, was about the night-covered streets. And lucky for her Ichigo arrives. But Rukia's luck can only take her so far.
Ichigo continues his duel with Renji. He has underestimated this Shinigami one too many times. When overwhelmed he is driven into a corner. And as the killing blow is about to be met, the calm Byakuya steps in. Only problem is... he's too swift for you to notice before you're impaled.
With Rukia's leaving, everyone's memory seems to have vanished as well. Only those who will be key players later have been able to remember. Ichigo needs training and luckily with school out, Urahara Kisuke will put him through some hardships.
Ichigo trains with Urahara. He is underground trapped in the hole with 72 hours left until his life chain will come to its end. Held by a binding spell, he waits while Jinta and Ururu tease him. When his chain is no more, he goes though the process of becoming a Hollow. In his mind Ichigo finds that he has to find the shinigami box or he will become a Hollow. After he finds the box he comes out of the hole a semi-hollow, semi-shinigami. He breaks the mask and Urahara moves on to the third lesson: defeat Urahara.
Ichigo finishes his training with Urahara and learns how to control his Soul Slayer. Seven days after his training is complete Ichigo, Orihime, Chad and Uuryu prepare to leave for the Soul Society with Yoruichi-san as their guide.