Chitose Is in the Ramune Bottle, Vol. 6 (manga)

Leave him. Now.' Saku Chitose and his fake girlfriend, Yuzuki Nanase, know they're playing with fire by trying to smoke out a potential stalker...but when creepy photos are delivered to Yuzuki's house along with a threatening note, things start to look serious. And as if that wasn't bad enough, Yuzuki's basketball shoes go missing right before a game! It's now up to Saku to solve the case-though perhaps he's missing a few too many puzzle pieces...