1x3 - Mitsudomoe

A boy named Yuudai Chiba catches a glimpse of Hitoha's erotic book and wants to see more of it, his friend Shinya Satou getting confused and assuming she wants to see her panties. Through certain events, Hitoha ends up meeting occult fanatic Sakiko Matsuoka, who mistakes her as being able to see ghosts. They end up sneaking into the pool before it opens, with Sakiko assuming Hitoha is trying to exorcise spirits, when she is actually drowning. During swimming the next day, the triplets forget their underwear and jump to the conclusion that they were stolen. When their suspicious looking father, Soujirou, arrives at school with the panties, Mitsuba is too embarrassed to admit losing them and implies he is the thief, getting him arrested.