An older brother who really wants to date his younger sister, Miiro. She is a younger sister who hates her brother who is always secretly filming her and confessing to her. One day, Miiro, who broke up with her boyfriend, accepts her brother's confession, saying, ``If it's just for a month...'' Unbeknownst to them, this is the beginning of a forbidden relationship that cannot be reversed. An incestuous life that began from that day that she could not tell her parents. Miiro gradually becomes obsessed with her brother and cannot live without her brother.