Black Jack is alive because his mother, Mio's pendant stopped the bullet from hitting him. He operates on the doctor's mother and discovers a Type Hydra artificial heart. It is a heart that keeps on pumping even when it is extracted from the host. They replaced the Type Hydra with another artificial heart that Black Jack requested and saved her life. They discover that the Type Hydra was designed by Hazama Kagemitsu, Black Jack's father through a microfiche that was inside Mio's pendant. The doctor's mother tells Black Jack how his parents met and how she got the artificial heart.