2 x Bone

A new species called "Eclipse" has emerged, driven to destroy humanity. Kurusu Kenji, a scientist, led an organization to combat them by developing "Osteon"—Eclipse-like beings that follow the orders of the humans whose DNA they are made from. After Kenji's death, his assistant Rokuko Kidogawa seeks out his estranged teenage son, Akira, who resents his father for abandoning him. Due to Eclipse attacks, Akira is forced to accept an Osteon from Rokuko. He gradually becomes involved in the organization, which expects him to take over his father's role. While Akira and his Osteon may not care about saving humanity, they are determined to avoid defeat.