Koichi, who felt empty from constantly going back and forth between his work and home, was sexually assaulted by a woman on his way to work one day. Excited by the stimulating pleasure he had never experienced before, he couldn't resist and ended up doing it again. However, the woman he was sexually assaulted was Akari, a female employee of a client company. With his weakness exposed, Koichi was forced to accept the sexual assault on the train as she told him to. Koichi gradually became absorbed in the twisted and extraordinary life with Akari, who was smiling and not caring about the people watching her.