"Will you make a contract with me?"

In a remote rural area of ​​19th-century France, Nini, a girl abandoned by her parents, was dying. At that moment, a beautiful demon appeared before her. His name was Dantalion. He was a thoughtful veterinarian specializing in magical beasts, with a sweet tooth. Nini made a contract with Dantalion and became a demon's familiar in the demon world—preparing herself for a harsh life. However, she was unexpectedly treated with great care and protection, and little by little, the frozen parts of her heart began to melt...

This is a twisted yet heartwarming master-servant story woven by the sweet demon Dantalion, the lazy houseguest demon Belphegor, the human Nini, and the magical beasts.

(Source: Kadokawa, translated)