magnum's manga / #Orphan(14)

Uke has younger siblings 20 years younger than him who live with their grandmother after their parents' passing. Seme was once rejected by uke in high school for being so much smaller than uke

Protective Vampire Seme falls in love with Carefree Uke and makes him his spawn and partner. “Mortally wounded trying to prevent what he thought was a mugging, Haru's life is saved by the vampire Akihito, with one small drawback; he is now a vampire too.”