Kuro Gal ni Natta kara Shinyuu to shitemita

This invincible duo walked down the street with confident strides, leaving girls swooning in heaps along the roadside. And really, who could resist them? One was a sporty, tanned, and gregarious blonde; the other—a fit, cocky, and charming brunette. They picked up girls together and never knew rejection.

Recently, however, the blonde, Shion, began to notice that girls were increasingly favoring his calm and seemingly dependable friend, Rui, while ignoring him entirely. Frustrated by the cold shoulder from women and plagued by jealousy, Shion gets drunk—only to wake up the next morning and find he has turned into a girl! He has absolutely no idea how to get his original body back.

In a panic, Shion does the first thing that comes to mind: he begs Rui for help. But Rui... declares that there is no problem at all and nothing to fix! After all, a best friend is a best friend, even in a girl's body, so there's no need to worry. Instead, they should seize this chance and make the absolute most of the situation! The only catch is that Rui will be the one exploiting, involving, and enjoying it all, while Shion will have to surrender to his friend's mercy. As it turns out, his female form simply cannot resist the irresistible male charm of the seducer Rui.