Akira Amaterasu and the rest of the gang are back! Newly engaged couple, Akira and Mizuki, are preparing for their new future. However, Akira is beginning to wonder if she is really ready for a married life and begins to doubt herself. However, with her dearest friends, Aoba, Koujaku, Noiz, Clear, Mink, and Ren at her back, she is reassured. However, a relentlessly strong and large gang, who take other gangs' territories by force, called Forsaken, are making their presence known and their leader has his eye on Akira. After an encounter, Akira is captured by Forsaken and it's up to Aoba and the others to band together in hope to find her and bring her home. Meanwhile, Akira struggles to keep her will strong and hopes high, but she soon learns that she is becoming something less than herself, due to the mental and physical abuse she is receiving. It's a race against time and Aoba, Mizuki, and the others must hurry and find Akira, before she forever loses herself.

The only solution to save humanity is to leave plague-ridden Earth for good. But can a plan born out of desperation bring back the lost innocence of the human community? Fiona is a survivor, immune to the virus that ravaged the population of Earth. Caught and used as a test subject, her bleak outlook on life changes when she becomes part of a secret development team. Their task? To find a new home for the remaining humans.