Is it Wrong to Try to Pick Up Girls in a Dungeon?(2013)

Dungeon ni Deai wo Motomeru no wa Machigatteiru Darou ka

Bell Cranel is just trying to find his way in the world. Of course, in his case, the "world" is an enormous dungeon filled with monsters, below a city run by gods and goddesses who have way too much time on their hands. He's got big dreams but not much more when a roll on the random encounter table brings him face-to-face with the girl of his dreams--but what does a beginning adventurer have to offer a brilliant swordswoman? And what if the lonely goddess who sponsors his solo adventuring gets jealous...?!

(Source: Yen Press)

Note: The manga got discontinued due to issues between the mangaka and the editorial.