THE HEROIC TALE OF AN UPSTART EXPLORER IN A WORLD FULL OF DUNGEONS is a Manga/Manhwa/Manhua in (English/Raw) language, Action series, english chapters have been translated and you can read them here.
Modern Japan where dungeons occur. Hayato Amahara, a 16-year-old junior high school graduate, is a poor explorer who sips the slime he has hunted and lives in a ragged house in the accident property. However, when he met a mysterious beauty, Hexa, his life turned around! It was a “weapon creation” that can create weapons! Unique beautiful girls gather around him!?