Summary Kanojo ni Naru Hi from Kainu Manga
Kanojo ni Naru Hi summary: Miyoshi is always competing and losing against his childhood friend, Mamiya, who is good at everything. One day, Mamiya collapses from illness and is hospitalized forseveral weeks. When he returns to school, it turns out he is genetically female, and has decided to try living his life as a girl now much to Miyoshi's horror.
