Mayoi Neko Overrun!

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: MU)

After finishing work on the 9th novel, illustrator Peko quit and the subsequent novels featured different artists to fill in the role; Yasu for the 10th volume, Hekiru Hikawa for the 11th and Misato Mitsumi for the 12th and final volume.