Arakawa Andâ Za Burijji (2010)

Kou Ichinomiya has always lived according to the creed of his wealthy, successful family: never be in debt to anyone. But one day, under the Arakawa Bridge, his life is saved by a homeless girl named Nino. In order to pay her back, Kou promises to be her boyfriend; and thus begins his new life under the bridge.