Katsubou Anima Gemella

Kaisei Hijiri, an alpha, has issues getting close to omegas because he feels guilty over a traumatic incident from his past. Then one day, his senpai tricked him into going to a male omega brothel. While there, he meets Ryuuji, a slutty macho prostitute, who is surprisingly different from the other omegas Kaisei met in the past. Will this encounter throw Kaisei into an even darker abyss...?!

(Source: Takeshobo, translated)