Hana and Tetsuya, who have lived in the same neighborhood for a long time and were childhood friends, became siblings when their parents got married. Hana, who suddenly became family, built a wall with Tetsuya and felt lonely. . Out of curiosity, she offered to pretend to be a doctor again and let Tetsuya touch her massive breasts... Since that day, I have been caught up in my little brother's blue sexual desire that I can't control.