To Be a Power in the Shadows! - Chapter 120

Bai Aoxue, the best mercenary in the 21st century, is accidentally sent back to the Chengxi Dynasty in Great Continent due to an explosion in her mission, and trapped in the first daughter of Prime Minister. After her rebirth, she is set up by her father to marry the 5th prince Jun Yeyan who wears a mask all day long.
In the face of bloodthirsty enemies, discord between brothers, collusion among courtiers and invasion of enemy state, can Bai and Jun resolve the crises? What will happen to their political marriage? How will the fierce battle for the throne end?
With many twists and turns, the book brings you to experience palace revolution, love and hatred thousands of years ago.

- Description from Novelupdates

Based on the popular Vocaloid song .

Rin, a young angel (presumed female, but angels don’t have clear genders) falls in love with a young human girl, Miku. However, their love is considered taboo, and so, Rin makes a deal with the devil to be reborn as the human boy, Len, in order to be with Miku. However, their happiness together is short-lived, and even that soon ends in tragedy.

A 30 year-old construction foreman and company worker, Satou Tarou dies from an unexpected accident. However, he receives a cheat-like ability from a god-like existence which allows him to cast healing magic and the knowledge to produce potions.

Using his newfound powers within this new world, Tarou accumulates a surplus of wealth and changes his name to Tauro. Setting his sights on the pleasure quarters of this parallel universe, perhaps the beginning of a new legend is on the rise….