Tsunakawa Souji

At the research institute KOKON, he is in charge of the development of combat androids "EXTRAs", as well as being their guardian.
Despite young age, he has a talent for genetic engineering that stands out among the researchers.
He is an outwardly bright and intellectual person, but harbors various doubts and internal conflicts. He tries to treat the three EXTRAs under his care like family.