In the mysterious town of Luvilia, where displaced oddities gather, a poor alchemist named Alfred finds himself at the mercy of Shin, the strongest vampire and the town's ruler. After losing his money, home, and nearly his life, Alfred is reluctantly saved by Shin only to be forced into a servitude contract. The condition for breaking this contract is to provide Shin with the feeling of genuine happiness in life, which is the vampire's only weakness. Bored with his long existence, Shin craves a death so sweet it grants him a delicious ecstasy, ordering Alfred to create the ultimate chocolate.

Alfred is a genius alchemist and a foreign student at the Royal Academy. He is blonde, wears glasses, and possesses an overconfident personality with a fondness for women. However, beneath this exterior lies a serious and intensely curious craftsman who, once determined, pursues his goals to the end. Coming from a military family, he was trained from a young age and is a top-tier marksman. His master, Shin, appears as a gentle man but is in fact dark and twisted, viewing humans with the same fondness one might have for a cat or dog. He harbors a particular, sadistic affection for Alfred, desiring to see him suffer.

The narrative follows the dangerous back-and-forth between the two men as Alfred races to create a deadly yet exquisite piece of chocolate before he is either killed for being useless or completely subjugated. What begins as a forced chore evolves as Alfred becomes engrossed in the infinite possibilities of chocolate, experimenting with nuts, rum, orange peel, and more. The conflict explores whether Alfred will succeed in killing the vampire with a sweet morsel first or be forced to live as his servant forever.

The story is divided into notable narrative arcs. The first part focuses on the initial contract and the fundamental exploration of chocolate making. A second part introduces a werewolf boy and a struggle related to chocolate, followed by an arc involving cursed fanfares from elegant ladies. Subsequent arcs delve into the discord between the alchemist and the vampire, leading to a significant turning point concerning the death of the young alchemist and the subsequent change in the Vampire King. The final documented arc describes an endless, mad banquet brought about by a black jewel.