Dokidoki Kyoudai Life

This is a heartwarming 4-koma story about a cute & short (very short) older sister Kawasumi Ayuko and her absent-minded younger brother Kumao, though they aren't related by blood. Ayuko has an intense brother complex, and likes Kumao more than anything, but Kumao is too young to be interested. Will the relationship of these two adopted siblings become one of romance?