Kimi ga Doutei dakara

Shiina, who prefers the company of the innocent and inexperienced, has a policy to just hook up, leave, and never get serious with anyone. That is, until he meets Sota, a hot, inexperienced college student. Shiina happily takes Sota to a hotel for the night, but isn't able to go all the way with Sota after seeing the big gun he's packing. However, Shiina can't let someone so good (a hung inexperienced hottie) get away! Shiina promises Sota he'll be ready the next time, but finds himself drawn more and more to his sweetness!

(Source: Renta!)