Mayoi Neko Overrun! - Yabuki, Kentarou

The story revolves around Takumi Tsuzuki, a boy who lives with his older "sister" Otome, although the two have no blood ties between them. Otome manages a run-down confectionery store called Stray Cats. One day, Otome picks up a mysterious beautiful girl off the streets.

(Source: ANN)

Mayoi Neko Overrun! is based on Tomohiro Matsu's light novel series of the same title.