Kokuyou-chan to Shiratama-kun no Kawatta Kankei

Kokuyou-chan is a guy who enjoys crossdressing as a girl. Shiratama-kun is a guy who's super popular with the ladies. These two are childhood friends, but one morning, Shiratama-kun awakens to discover that he has transformed into a girl! What will Kokuyou-chan do?! Can love overcome the difficulties caused by this sudden gender change?! Source: Houbunsha