Jun Sakakibara

Dr. Akiba, a rather perverted scientist, developed a series of sex robots, and Type 100 is his newest creation. She has highly advanced artificial intelligence — so advanced that she refuses to become Dr. Akiba's sex slave as he had designed and escapes from his lab. She meets college student Shunsuke Kubo and decides to stay at his apartment. However, as she is designed to be a sex robot, she interprets everything Shunsuke says in a sexual manner.

Aya, who has come to Tokyo on a school trip, uses her free time to go and visit her brother, Jun, who she was separated from after her parents' divorce. Although Aya has a boyfriend named Nobu, she can't help but think about her brother. Aya had harbored a secret crush on her brother since childhood and wanted to confirm her feelings upon their reunion. Meanwhile, Aya's boyfriend was not pleased. As a virgin, Nobu had planned to have sex with her for the first time during the school trip, but Aya went to see her brother instead. On the second day, Nobu secretly followed her. He then witnessed Aya and Jun in a passionate embrace in Jun's room…