Ryo wakes up one day to find himself transported to another world full of monster girls. Although their power far surpasses that of any humans, Ryo has his own ability—the "Charm" skill, which forcibly increases his affection level with all monster girls! Using this skill, he seduces all kinds of monster girls and builds a harem to get revenge on all the fantastical creatures that attacked and brought his home to ruin...!