I Got a Monster Princess in My Seventh Life.

Synopsis

Hugo is stuck in a time loop, forced to relive the same life up until the moment he is slain by one of his own relatives. But, after swearing revenge on his murderous family during his seventh reset, he meets a beautiful girl. According to rumor, this girl is a monster in human flesh, but he agrees to become her servant all the same. The birth of their partnership heralds an intertwining of fates, and Hugo's life will never be the same again... (Source: Yen Press)