Fall in Love with the Cold-Blooded Queen

She was originally a simple and beautiful girl, but after losing her grandmother, she became cold-blooded and terrifying. She is the queen of the killer world! He was originally a sunny and handsome boy, but after losing his cousin, he became ruthless and became the emperor of the killer world! When he meets her, and when she meets him, what kind of sparks will they create? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.