The most powerful and terrible devil among all the devils is Suma, the devil of sleep, who can make you sleepy no matter how long you’ve slept!

Suma, who hadn’t fallen asleep for the past six hundred years, finally takes a good rest when he meets a human female who his spell wouldn’t work on.

“Such a great human vitamin! Be proud of yourself, human.”

Suma treats her differently from other humans, but one day, he finds himself feeling emotions for this poor and humble creature.