Shuichiro Keido is a major character, who is head of the Antibodies in GHQ. He at first seems minor to the plot, but is revealed to be a major antagonist.
He is a middle aged man, with greying hair, and a medium sized mustache. He usually wored a lab coat, when in GHQ.
As a graduate student, Shichiro was isolated by his intelligence, and hardly interacted with anyone. Till he met Kuruso Ouma, who was the only person, whom was at his level of intelligence. They became the best of friends, both of them discovering the Apocalypse Virus. But their friendship went cold when Yu explained the virus and that Mana would be the new Eve and that Shu would be the new Adam, Shichiro was jealous that the new generation of humans would be based on his friend's DNA. To prevent this he would gather many boys including Gai, and run experiements, including infecting them with the virus, to create an Adam for Mana. When he finds out that Kuruso has discovered more about the virus than him, he flies into a jealous rage, killing his former friend and stealing his notes.
He is very stoic, and usually keeping a calm and collected face. The first thing that stands out about him, is his friendship to Kuruso. At first he was very happy, to have made friends with Kuruso. But his feelings eventually turned to jealousy when Yu revealed that his friend's DNA would be the basis of the next generation of humans. This was multipled when Kuruso was revealed to be ahead of him in their research of the Apocalypse virus. As a result he gains a desire to for the Fourth Apocalypse to occur, with him as Adam.