Mogusa-san(2013)

High school boy Koguchi Torao sees Mogusa Minori, a quiet, reserved girl in his class, walk into the restaurant run by his family and order an unbelievable amount of food, and even more surprisingly, sees that she keeps unagi pie (a sweet biscuit made with powdered eel) in her wallet?!

The story revolves around Koguchi and Mogusa's meetings in daily life and Koguchi's observations of Mogusa's unbelievable (and quite eccentric) eating habits.