Ishizue, Arika

He is the protagonist of the story. He lost his left arm two years ago, in the events preceding DDD to his little sister, Kanata Ishizue. After one and a half years of rehabilitation, he was then discharged from the hospital and began searching for an artificial arm. Mato, who is in charge of him, introduced him to Kaie Karyou, saying that he was a dilettante with rare prosthetics.