The Marquis’ Eldest Son’S Lascivious StoryKoushaku Chakunan Koushoku Monogatari - Isekai Harem Eiyuu Senki ; 侯爵嫡男好色物語 ～異世界ハーレム英雄戦記～

A Japanese salary man was reincarnated in a different world with swords and magic. He reincarnated into the family of a powerful noble. One day when he became twelve years old, he was suddenly summoned by his father.