One Piece: The Soul Purchasing Pirate - Chapter 54

Having lived a normal life all his life and died without being able to fulfill his desire and when he’s given a task by a god, watch how he takes the protagonists girls while making it hard for the hero.

After his death, Bern awakens 10 years into the past as the third prince of Kailis, the enemy country.

Descent of the Phoenix – 13 Years Old Princess Consort

The strongest female assassin from a special assassination force met her death one day on a mission. To her surprise, she woke up in the body of a 13 year old girl, Mu Rong Liu Yue. Through Liu Yue’s past memories, she found out that she was bullied due to the huge birthmark on her face, even though she came from a renowned family. Liu Yue was beaten to death by her own cousin, and that’s how she managed to enter Liu Yue’s battered body. The assassin then decided to live her life as Liu Yue and swore to avenge her death.

- Description from Novelupdates