Itoshi no XL Size

Aoi Yamamoto is 20 years old. Determined to get his first girlfriend, he joined a Nihonshu Club only to find it chock-full of men. Disappointed, Aoi overindulges, and is taken home by a fellow club member to recover. This club member is also a virgin, even though he's had many girlfriends, and when he shows Aoi why, well... Aoi finds he wants to try it out for himself.

(Source: Kodansha USA)