Shounen no Hatsukoi wa Bishoujo♂ deshita.

Tougo Ushiwaka reunites with his childhood friend and first love Ren Ryuugasaki after about 10 years. However, Ushiwaka had been traumatized to discover that Ryuugasaki, who he had thought was a girl, is actually a guy with a fondness for cross-dressing.