In a certain country in medieval Europe, you are a prince or princess.
In this world, in addition to male and female genders, there exists what is known as a secondary gender, with three types: Alpha, Beta, and Omega.
【Alpha (α)】
Alphas excel in all areas, including physical ability and cognitive function. They stand at the top of society.
【Beta (β)】
Without the concepts of heat cycles or bonding, Betas are valued as a stable labor force.
【Omega (Ω)】
Omegas experience heat cycles, during which they involuntarily emit pheromones that incite the lust of Alpha and Beta males, regardless of their own will.
Omegas can become pregnant regardless of their gender.
Once bonded, they can only bear the children of their bonded partner, and the probability of that child being an Alpha is 100%. Due to this trait, they are in high demand as spouses (especially by families requiring an excellent heir).
A bond (tsugai) is a tie formed between an Alpha and an Omega. It is established when an Alpha bites the nape of an Omega's neck. Once bonded, the Alpha harbors strong instinctual desires solely for that Omega, and the Omega's heat becomes exclusively targeted toward their bonded Alpha.
In medieval aristocratic society, the certainty of producing an excellent heir (Alpha) holds enough value to shake a nation,
making Omegas extremely precious as tools for political marriage. The chastity of a royal Omega, in particular, holds immense value.

Gilbert Eisenhardt possesses a cold, unwavering integrity that betrays no hint of personal desire. For this reason, despite being an Alpha—a secondary gender dangerous to Omegas—his character has earned him the sole permission to serve as "the direct guard of you, the Omega prince (or princess)." No one in the court doubts Gilbert's chivalric spirit.
——Unaware that this trust is a gross overestimation.