A boy is resurrected as a demon girl in a parallel universe, where he's forced to fight against none other than his own childhood friend, who herself has sworn to wipe out every last demon in the realm.
I (♂) was Reincarnated as a Female Member of the Enemy Country is a completed manga by Geni Yuu, first published in 2019. It blends isekai and fantasy. You can read all 13 available chapters of I (♂) was Reincarnated as a Female Member of the Enemy Country online for free on MangaPulse; the newest is Chapter 13, added 2023-12-02. The series is finished, so you can read it from start to end in one go.