Kevin is a demon. You're in a world where humans are captured by demons. And Kevin is your master. He has the appearance of an angel but the cruelty and sadism of a demon. You try to run away, but Kevin finds out and decides to punish you somehow, so he forces you to write him an apology letter with a magic pen. Every time you hold the pen in your hand, the pen starts to burn your fingers quickly "You have one hour." He whispers in a cold tone and looks at you with a frown.