The dark untold story of Steins;Gate that leads with the eccentric mad scientist Okabe, struggling to recover from a failed attempt at rescuing Kurisu. He decides to give up and abandons his lively scientist alter ego, in pursuit to forget the past. When all seems to be normal, he is seemingly pulled back into the past by meeting an acquaintance of Kurisu, who tells him that they have begun testing a device that stores the memory of a human and creates a simulation of them with their characteristics and personalities. Okabe begins testing and finds out that the simulation of Kurisu has brought back anguish and some new unexpected tragedies.
Zero is a side story that explores events from the Beta Attractor Field's future that contribute in making the end of the original story possible.
Though WWIII is on the horizon, Okabe attempts to live a normal college life. However, a newly developed AI is about to shake up his world.
After a chance encounter with Maho where they discover knowing someone in common, Okabe has his first face-to-face with her special AI, Amadeus.
Mayuri tries to bring everyone together for a Christmas party at the lab, but Okabe has a rude awakening.
While OkaRintaro briefly has a vision of a world line where he is caught up in the middle of a war, which he eventually comes to realise was his Reading Steiner taking effect. Meanwhile, Suzuha explains to Daru that she is looking for Kagari Shiina, Mayuri's future adopted daughter who time-travelled with her from the year 2036 but became seperated from her in 1998. As Rintaro decides to help with the search, he gets a call from Ruka Urashibara about a pressing matter before finding Moeka before his doorstep. be is left with more questions than answers, Suzuha recruits help in her search for an unexpectedly close person.
Their search continues as New Years swiftly approaches, though Ruka's dilemma with a certain guest might make matters worse.
Now that the girl's identity is known, Okabe and friends kick off the New Years with a shrine visit and party to never forget.
As Okabe seeks answers regarding the attack, trouble with Amadeus brings a surprising turn of events.
Okabe is given a bittersweet reminder that in changing world lines, sacrifices must be made.
It will take time for Okabe to identify the attackers and their motivation, but the impending crisis of WWIII forces Suzuha to resort to desperate measures.
After reinforcements are called to clean Maho's disastrous room, her and Okabe's Akihabara date ends with a surprising confession from Maho.
Okabe must convince Maho to give up her prized possession, but an unexpected danger has them negotiating for their own lives.
Kagari attempts to track down the origins of a song in hopes that she discovers her lost memories.
After finally obtaining a hint into Kagari's lost past, Okabe ends up discovering much more than he bargained for.
Shocked by a surprise attack, Suzuha and Daru look to America as their last hope to save the world.
Fed up with her Dad's passiveness, Suzuha must make a man out of Daru before Yuki ends up with somebody else.
Okabe's stubbornness causes fists to fly and tears to be shed as the deadline for using the time machine swiftly approaches.
As Suzuha sets off to finish her mission, Mayuri finds determination of her own. But then, disaster strikes.
All hell breaks loose over the time machine when a villain from the future haunts the past and unveils their devious plan.
War and disaster has come, and the only way Okabe can stop it is to rely on his friends, determination, and hope.
Okabe awakes in a cold, lifeless world where he finds his friends struggling to survive amidst all the chaos.
Setting forth on a long and arduous journey, Okabe seeks to rekindle his hope and revive what all had thought gone.
In their struggle to save the time machine, the lab members brainstorm to circumvent convergence but realize it cannot be done without sacrifice.
Okabe and his friends must battle against fate in the past, present, and future to find Steins Gate and reunite the lab members once and for all.