Riko – Schoolgirl, brother, sober, neat man … The two decided to live together under the same roof only for a sudden turnaround due to the remarriage of each other's parents. Riko, a dull brother who suddenly decides to live with her, is a child. During the three days when her parents were absent during the couple's trip, Riko was forced to have sex by voyeurizing the electric massage machine she had hidden and masturbating in her room. However, there was a surprising match between the two … Riko and her brother's gender compatibility is truly the best. Tsundere sister during the rebellion was hated by her brother-in-law!