Playboy na Ore ga Onna ni saremashita!! I'm a Playboy, and Now I'm Forced to be "Bottom"

Synopsis

Tsutsui, an ultimate playboy, gets drunk in front of his senior Tamura and is raped halfway through. The kind senior he thought Tamura was, turned out to be a sly, gay person! Tsutsui is in shock, Tamura still has his eye on him, and he can't help but feel anxious. At the same time, he meets Shinoda who shares the same plight as him, Shinoda proposes that they pretend to be lovers. While thinking that it's no laughing matter with another man, Tsutsui's back gradually starts to ache...?! (Source: Kadokawa, translated)