- An older brother who desperately wants to date his younger sister, Miiro. - A sister who hates her brother who always takes voyeurs and confesses. One day, Miiro, who broke up with her boyfriend, accepts her brother's confession, saying, "If only for one month ...". Without knowing that it was the beginning of a forbidden relationship that could not be returned. An incestuous life that I can't tell my parents that started from that day. Gradually, Miiro becomes captivated by her brother and cannot live without him. After a while, my brother, who left home, suddenly came back with his fiancée ... At that time, Miiro ...