One day the protagonist returns home and discovers a mysterious gloryhole in the wall between his room and his little sister Sayaka's room. He peeks through and sees Sayaka masturbating. The next day, he gains courage, sticks his cock through the hole. Sayaka pretends it's a mushroom and starts licking and sucking it. The tsundere sister who can't express her honest feelings toward her brother finally gets her deepest desires fulfilled through the wall. They proceed to intense brother-sister