[Mello twists his head as far away from B as he can]

Shinigami live in a separate realm from humans where they watch the world. They have eyes like yours that let them see people's names and when they're supposed to die. To kill humans Shinigami write their name in notebooks called Death Notes. Humans can use that power too if they get a hold of a Death Note. You have to write down the person's name while thinking of their face and that person dies. Kira used it to execute millions.