Elf Dorei to Kizuku Dungeon Harem: Isekai de Netotte Nakama wo Fuyashimasu

Mars, a boy who was reborn into this magical world, is on a quest with his elf slave, Lilia. His goal is to conquer the world's seven greatest dungeons and obtain the forbidden book of magic, which contained extraordinary powers. However, he kept falling behind in his quest progress because he spent