Jaku-chara Tomozaki-kun - Volume 2 Chapter 2 part8

[Across the Stunning Beast Princess: Phoenix Against the World]

She, First Princess residence’s only legal daughter, yet known as a waste throughout the whole country!

When her cold eyes opened, she is the 21st Century’s most dangerous genius assassin!

When the sickly young miss exposes an edge, she is absolutely brilliant, and countless men and women in the world greatly admire her……

He is the absolute king of the night, cold blooded and ruthless. In troubled times, he by chance meets her, a zither and flute ensemble, since then in heaven and earth, life and death go hand in hand.

- Description from Novelupdates

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.