Kuro Gal ni Natta kara Shinyuu to shitemita.

Shion and Rui have been childhood friends for years and spend their college life chasing girls together until a strange drug transforms Shion's body into that of a woman. What should have been a temporary accident completely changes the boundaries of their friendship. Rui knows exactly who is standing in front of him, yet the distance they maintained for years begins disappearing anyway. As they investigate the transformation and Shion starts shifting unpredictably between male and female forms, both are forced to confront how Rui now sees him and how Shion's own feelings are changing. The real question gradually stops being how to restore his body and becomes what will remain between them when it finally returns to normal.