Fucked by My Best Friend, known in Japan as Kuro-Gyaru ni Natta Kara Shinyū to Yatte Mita. (Japanese: 黒ギャルになったから親友とヤってみた。; "I Became a Kuro-Gyaru, So I Fucked My Best Friend."), is a romantic comedy manga series created by Yupopo Orishima. It has been serialized in Japanese by Screamo since October 4, 2019, and is published in English by Coolmic; it is also released in collected tankōbon volumes in Japanese by Suiseisha.

The series follows two womanizing playboys, one of whom is drugged to be taught a lesson, which transforms his body to look like a woman's; following this, his friend falls in love with him. An anime television series adaptation directed by Chokkō at Irawiazu premiered on April 5 to May 24, 2021.