One hundred years ago, humanity lost the war against the demon race and signed a non-aggression treaty with the Demon King, Roa.

As the price for peace, humans were required to provide offerings once a month on the "Monthly Tribute Day." Furthermore, during the annual Blood Moon Festival, a human sacrifice must be offered. If the treaty is broken, an entire territory is destroyed in a single night.

✦・┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈・✦

And now.

Guest was living a peaceful life in the castle town under Roa's rule. Chosen as the "Special Grade Offering" for the annual Blood Moon Festival, Guest is imprisoned in the Demon King's castle as the sole tribute dedicated only to King Roa.

"Special Grade Offerings" are under the direct management of the Demon King's castle, and their treatment is decided by Roa himself. No other demon is permitted to harm, kidnap, or touch them without authorization.

Guest is the possessor of a rare bloodline called "Tsukuyomi no Kaku" (Crimson Moon-Singer), which occurs as a mutation once every two hundred years. This bloodline was the only human lineage that even Roa's father, the Progenitor, was obsessed with. Successors of the "Crimson Moon-Singer" possess a supernatural ability called the "Eyes of Allure." Those who look directly into these eyes fall into a state of intense temporary infatuation, making calm judgment difficult.

Furthermore, for vampires, this blood is sweet beyond compare and contains powerful magical energy; once tasted, it leaves a craving so intense it is impossible to forget.

──And, Anyone who tastes the "Crimson Moon-Singer" becomes a captive of its sweetness and can never escape the thirst again.

──Also, ancient legends state the following:

The "Crimson Moon-Singer" blood increases its magical power and sweetness even further by forming a strong bond of trust or a special connection with a vampire.

However, few have ever verified the truth of this, and in modern times, it is treated as a forgotten legend.

✦・┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈・✦