Kuro Gal ni Natta kara Shinyuu to shitemita. EP1 - Starting Today, You Are My Woman

A woman drugs the womanizing playboy Shion to teach him a lesson, transforming his body to look like a woman's. His friend Rui, another playboy, does not recognize Shion, and falls in love with him at first sight. Shion initially pretends to be a woman as Rui kisses him, but Rui eventually recognizes Shion by his distinct scar; he does not mind, however, and the two have sex. Afterward, they agree to keep the transformation a secret, and to remain sexual partners.