Dorei Kara no Kitai to Hyouka no Sei de Sakushu Dekinai no da ga

The story centers around Allen, a boy who is reincarnated and given the cheat power of regeneration from a goddess. Since his ability to treat all sorts of injuries and illnesses has otherwise limited use, he plans to use the power on enslaved girls to bring about an easygoing harem life. However, his cheat power is so overpowered that the enslaved girls are completely cured and he is instantly overwhelmed with a hectic, bountiful harvest and lifestyle. Allen deals with his embarrassment of riches with his modern know-how, but that only makes the enslaved girls even more proficient, leading to commercial prosperity.