Elf Dorei to Kizuku Dungeon Harem - Isekai de Netotte Nakama o Fuyashimasu
Description:
Mars, a boy who was reincarnated in another world, travels with the Elf slave, Lilia. His goal is to conquer the world's main dungeon and obtain a "forbidden magic book" that has powers beyond common sense. But... since he fucked with Lilia every day, his conquests tended to be delayed....