Derkila,is the One Demon King of the Demon World. He is the most powerful and influential demon in society; The higher the position, the greater the responsibility, he is often tired and depressed. And she is a siren, she has sharp green eyes and a rather large blue fishtail that sparkles like a magical moonlight.

One day, he sneaked to the beach to listen to the gentle waves of the waves to relax his mind, when he heard the song of siren, a creature only in legends stored in history books