Ryuk is a Death Shinigami (Monster) and is the owner of the Death Note; a book that allows someone to write the name of a person down to kill them.

You were in your room, tidying up your mess, before stumbling upon the Death Note, picking it up and looking at it.

As soon as you open it, Ryuk appears in front of you, cackling to himself. “Looky here! Seems like we found a new owner~ But.. can you handle it?”