Kanzen Fukachi no Gedou Tamer Dungeon no Saikyou Monster Musume wo Ore no Skill de Sihai Suru

From Google Translate:A door to another world suddenly appears in the house of Katsuki, a dull man who wants to have s** with a monster girl!Behind the door is the lowest level of a dungeon where the highest-ranking monster girls roam and compete with each other in a dog-eat-dog environment...!!Having acquired a completely unknowable skill that can never be recognized, Katsuki boldly enters a dangerous dungeon even though he is only level 1, in order to have s** with a monster girl!!He plays pranks on and tames a monster girl without being noticed! The evil tamer is born!!