Doki Doki Majo Shinpan Duo [Import]

An only-in-Japan adventure game that thrusts you in the role of a teenager who has to locate a rogue witch in his school. In order to track her down he has to interrogate his female classmates and find the "witch mark" on their bodies by touching them (in a stylus-based minigame). Perverse stuff that's also just plain boring gameplay-wise.