Otoko Shika Inai Kuni no Alice

One day, high school student Arisumi suddenly loses consciousness and wakes up to find himself in the middle of an intense sexual encounter with his best friend, Oodate! Arisumi is confused, but just as Oodate said, "we've done it many times," his body has already been developed and he is swept away by the pleasure. On top of that, his sister has become his brother, the female idol has become a male idol, his best friend has become his boyfriend, and he has apparently been transported to a "world where only men exist." Wanting to somehow return to his original world, Arisumi is told that "if you recreate the situation you were in when you were tripped, you can return," so he ends up having sex with Oodate many times!?