Episode 21 is also known as Eclosion:Emergence.
As the combine forces of the Undertakers and the UN forces arrive at GHQ Headquarters, realizing the 256 Leukocyte satellites was a bluff, Shu helps Ayase into her new Steiner Endlave and promises his friends and allies that they will rescue Inori and stop Gai. As the UN forces attack, Gai uses Yuu, Kenji and Arisa voids to decimate them and Shuichiro orders the GHQ/Anti Bodies/Daath forces to destroy them.
Daryl is forced to join the attack in his new Gespenst Endlave due to having his void taken. Thanks to Tsugumi's void, Shu and his Undertakers/PMC allies manage to sneak inside and hack into the base system, allowing the UN the chance to counterattack. As Tsugumi group split up with Shu and the others, Gai prepares to get rid of Inori's memories before Mana can take over her body but ask her why she loves Shu.
Inori answers while she is grateful that Gai rescued her from the lab she was created and gave her a purpose in life, Shu showed her the ugliness and beauty in life and how hard he to amend his mistakes that made her love him. As crystals take over her body, Inori sings a song that only Shu can hear who leads them to the center of GHQ Headquarters. Shu is separated from his allies as Yuu confronts Shu himself while Kurachi, Haruka, Ayase, Argo and the rest faces off with Daryl and his men.
Yuu reveals that he is actually an embodiment of the will of the Daath organization, and impressed on how far Shu has done, offers him to become the new "Adam" and become Mana's mate which Shu refuses, leading them to fight. As Yuu uses his followers void to try and kill Shu, Yuu laments how Shu squander his chance to restart the human race all for a "doll" ("soulless, testless child" in English dub), but Shu counters back, telling him Inori is not a tool but a human being who was there when he was down and he will rescue her. Defeated, Yuu allows Shu to meet Inori before disappearing. Shu confronts Gai who reveals Inori has finally transformed into Mana.
- In the original Japanese before defeating Yuu, Shu said to himself that Inori is always by his side. In the English dub, Shu is shouting Da'ath of saying "I won't let you take her, I won't!".