Death Note (2006)

A god of death, known as shinigami, is capable of killing any person - as long as they see their victim's face and they've written their victim's name in a notebook called a Death Note. Being bored by this lifestyle, Ryuk went to the world of humans to find out how a mere human would use a Death Note.

A high school student named Light Yagami sees the Death Note and tests the notebook by jotting down a criminal's name in it. When he discovers that the criminal died as soon as he written its name, Light realizes how powerful and deadly this notebook could be.