Akatsuki wakes in the school gymnasium with no memory of the previous day. Himeragi is beside him on a futon, dressed in an old-style PE uniform with bloomers, and neither can explain why they were asleep there together. Meanwhile, several of the girls look into Vatler's ship, which has been found floating with no one aboard. A bloodstained baseball bat and a missing weapon make things stranger, and a purple bra turns up in Akatsuki's pocket. As various factions rush to make sense of the empty boat, the bat and the bra, the mystery keeps deepening. The single OVA episode mixes action, fantasy, supernatural elements and ecchi.