Kuro Gal ni Natta kara Shinyuu to shitemita.  

Seduced by My Best Friend, Fucked By My Best Friend, I Became a Black Gal So I Fucked My Best Friend, Kuro Gal ni Natta kara Shinyuu to Yattemita., 黒ギャルになったから親友としてみた。

Shion and Rui are known as the perfect duo when it comes to seducing women. Tonight was going to be another night of scoring with ladies for Shion, but he took a mysterious drug that caused him to transform into a girl! When he woke up, he discovered his new appearance and was shocked. Meanwhile, Rui searched for Shion, unaware of his transformation, and began hitting on him instead.