Cupid no Itazura Nijidama

A man who's still a virgin, has a very very rare disease that only allows him to have sex 7 times in his life. After he's used up all 7 of the chances, he'll never be able to have an erection and ejaculate, which means he will lose his ability to have sex for the rest of his life. So far, he has wasted 2 times while masturbating, so he's left with only 5 more chance to have sex. He has to save those precious bullets, but at the same time he desperately want to lose his virginity.

Included one-shot:
Volume 4: Senpai no Kanojo to Heya de