"Senpai, I'll dominate you to the marrow of your bones." Sumio Tachibana, an orthopedic surgeon (a resident), has spent his days as a sub controlling his desires to be dominated and controlled. However, he doesn't have a designated Dom, and remaining in this state will damage him both mentally and physically. Because of this, Sumio decides to visit a SUB-only club... There he meets his old high school junior, now a yakuza, Wanizuka Itsumi [DOM]. Since he doesn't have a designated dom he urges, "Let me become sempai's dom." ?! [DOM/SUB Universe] a trying story of a jealous young yakuza x a surgeon who really just wants to be spoiled?!