在即将面临废部的弱小吹奏乐部，以吹奏乐的甲子园“普门馆”为目标的一对青梅竹马·穗村千夏和上条春太。他们在努力练习以及募集新入部员当中度过着热闹的每一天，但各种谜团也接踵而至……。

Things look bleak for the school’s Wind Instrument Club until childhood friends Haruta and Chika step in to save the day. When they aren’t practicing to perfect their own playing, they’re working hard to save the club by recruiting new members. After a series of mysteries shock the school, they’ll have to add junior detectives to their already impressive resumes.