Kono Koi wa Fukami-kun no Plan ni wa Nai.

An unexpected love starting from an unplanned kiss. Fukami-kun is a smart, good-looking guy who's popular with the girls. But in actuality, he's a disappointingly stubborn boy who refuses to accommodate anyone else's schedule, leading him to be rejected even after being confessed to. One day, a strange girl, Higurashi Akio, is looking for her cat around the school grounds, and the two of them somehow end up kissing by accident. Unlike Fukami-kun, Akio doesn't seem to care about the accident at all. At first, Fukami-kun is irked by her attitude, but gradually comes to hold an interest in the capricious Akio. A youthful love story between a disappointing boy and a strange girl begins.

(Source: Houbunsha, translated)