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Shuichiro reveals to Segai that Ruppongi Fort is in fact a massive Void created by Mana Oma and gives him the Voiddata he wanted, releasing him from his services following the coup d'état of GHQ. Meanwhile, Shu seemingly remembers Gai who tells him to follow the blond youngster, Daath Gravekeeper, who along with Shuichiro intend on sacrificing Inori to awaken Mana. At this point, Daath helps Shu regain his memories. A much younger Shu is seen over looking the ocean on an island in Oshima with his sister Mana when they spot a small blond boy washed up on the beach. The boy turns out to be a younger Gai Tsutsugami who spends the summer with them at their beach house on the island and becomes Shu's best friend while falling in love with Mana. After experiencing the flashback, Shu finds himself in the crystal tower where Shuichiro has Inori bound. He explains that Inori was in fact a body created to for Mana (whose soul lies preserved thanks to the virus) after she is reincarnated by fusing her soul into Inori's body. At which point the secondLost Christmas would occur and the virus will annihilate all humans on Earth. Shuichiro then intends to be "Adam" and create a new race in the aftermath with Mana, "Eve". Daath then begins a ceremony to join them together in "marriage" which sparks another flashback. Mana tells Shu she loves and wants to marry him. In actuality, Mana was infected with the Apocalypse Virus which induced her insanity. When Gai learned about it, Mana threatened him not to tell Shu. Back in the present, Shu tries to stop Shuichiro and Daath but crystal-like plants controlled by Mana bind him. However, Gai and Ayase's Steiner arrive in the tower with help from Segai, which is his version of causing trouble for Shuichiro since he was basically ejected from his plan. As Steiner is destroyed, Gai helps Shu remember how the Lost Christmas incident began. On that day ten years ago, Gai asked Shu to meet him at a church to tell him the truth about Mana. However, Mana came instead and tricked Gai into shooting himself. When Shu arrives, the scene disturbed him and rejects Mana's offer to marry her and start a new race together by calling her a monster. Hurt, Mana goes berserk and spreads theApocalypse Virus over Tokyo before coming to her senses and destroys herself, unable to control her power. Feeling responsible for not helping Mana, Gai vows to become stronger while a traumatized Shu repressed his memories about Mana and Gai. Finally remembering his past, Shu helps Gai extract his Void, a gun that forces out other people's Voids. As Shu rescues Inori, Gai heads to the pod to free Mana's soul, Shuichiro tries to stop but is himself stopped by Daath. As Gai reaches for the pod but is stabbed by the crystals protecting it. Knowing he won't live much longer and wishing to accompany Mana in her last moments, Gai begs Shu to stab Mana's pod through his body with Inori's sword which Shu tearfully does. As the tower crumbles, and Gai finally holds Mana in his arms and they disappear together. Shu and Inori float to safety and mourn Gai's death.
