Uesugi-kun wa Onnanoko wo Yametai

Uesugi-kun is a boy who is as petite and cute as a girl. He has a crush on a girl he has known since childhood, but he overheard her saying, "Wouldn't it be so cute if Uesugi was a girl!" Uesugi-kun is not as tall as his other childhood friend Eito, nor is he as good at studies, and now he also has a broken heart. Uesugi-kun is depressed, so on his way home from school, he stops by a shrine and prays for a favor... A love-triangle romantic comedy featuring an overly cute, and now female, protagonist begins!

(Source: Ciao!, translated)