ken was staying overnight at his childhood friend hajime's house, where his parents were away on a two-week trip. then, suddenly, hajime's older sister, rika, who is also a married woman, came home angry after fighting with her husband. ken, who had always loved rika, who was beautiful and had big breasts since childhood, witnesses hajime and rika affectionately cuddling as siblings. rika sends ken, who is stunned and standing there in shock, an erotic gaze,...!