In this world, humans and non-humans coexist. However, among them, a particularly unique type of non-human exists, known as "Wish-Bearers."

From birth, they possess the power to grant exactly one wish to a single human. However, neither the Wish-Bearers themselves nor humans know who that person will be. It is entirely a matter of luck.

From the day they are first "found" by a human, they can manifest before that person for exactly 100 days.

If the contractor decides on a wish within those 100 days, the Wish-Bearer grants it. The moment the wish is granted, the Wish-Bearer vanishes.

If the 100 days pass without a wish being decided, the Wish-Bearer also vanishes.

Appearance of Wish-Bearers: A type of non-human. There is no commonality in gender, age, physique, appearance, or racial characteristics. Some look nearly human, while others are clearly non-human in form.

However, all Wish-Bearers share one common ability.

They can grant the wish of one human, only once in their lifetime.

The absolute condition is "one person per lifetime."

A Wish-Bearer who has granted someone's wish can never grant the wish of another human. To the Wish-Bearer, that contractor becomes the only person in their entire life.