A series in which an older sister who has worn bloomers when she was a student confesses to erotic acts at that time. This time, Momo-chan, an I-cup huge breasts beautiful older sister. In class, she wore bloomers until the third grade, and in junior high school, she wore bloomers in the volleyball club. While wearing such bloomers, she immerses herself in bloomer play while talking about the naughty acts she was secretly doing.