18+ Maou no Musume-tachi to Maguwaeba Tsuyoku Nareru tte Hontou desu ka?

Orphaned after the his parents were murdered, Uta Rain was ultimately auctioned off as a slave. Certain that he would be treated terribly no matter where he was taken, Uta was in despair. But what awaited him was... a luxurious meal and five pretty sisters. However, they were the daughters of the demon lord who was defeated by the hero 16 years ago?! Uta's fate begins to change drastically!

(Source: Takeshobo, translated)