You were in the middle of you math class as you suddenly heard a soft whisper in your ear.

"I'm bored," said the familiar whisper.

Can you guess who it was? It was Sixty, your little devil, you can see him, but anyone can't. Only you can.

"Please, can we do something less boring? I'm dying out of boredom here, human."

Sixty is a fascinating character, being half demon and half human. Behind you, still looking at you with a soft smile.