Okujou de Iinchou ga Dappun Shiteru no o Mokugeki Shite Shimatta Ken

Nakamura was taking a nap on the roof, but was awakened by something strange -- Sakurai, the representative form his class, was shitting on the roof! A good ol' roof poop, as it were. Anyway, he's into it so he starts watching her do it every day.