Ore no Level Up ga Okashii! ~Dekiru Otoko no Isekai Tensei~

Zarmen, an adventurer who can't level up decides to retire from the adventurer business. Furthermore, in order to graduate from virginity, he decided to splurge on all the assets that he had diligently saved up since his reincarnation at a high-class brothel. The woman who appeared in front of him was the finest woman he would ever have known. Thanks to her hospitality, Zarmen fully enjoys his first time, but at that moment, his ears hear a mysterious announcement... "Does this mean that the more 'seeding' I do, the stronger I get?"