Yoyota was a mercenary ninja who stalks and abducts Ampersand and takes him back to Japan on the orders of the mysterious "Doctor M". She is short-tempered and violent, going so far as to cut off a part of Ampersand's tail every time he misbehaves. Her parents were killed in a tsunami in 1983. As a teenager, she was caught breaking into the lab of Dr. Mann's father, who then arranged for her to receive training in the martial arts from The Perfect Circle, an organization formed in the 1940s by Emperor Hirohito as a countermeasure to the Culper Ring. In the "Motherland" arc, she reveals that one of the reasons she stays in Dr. M/Dr. Matsumori's employment is so she would be given a long line of clones, thus "(she) would never really die." She is stabbed in the head with a broken naginata by Agent 355.