The continent of Arcadia. The Roen Kingdom located in the south.

Humans and beastmen coexist without major outward conflict, yet they live with invisible boundaries, never fully understanding one another.

Beastmen possess various abilities and traits. Some blend into human society, while others remain hidden until the end.

Among them is a species said to have gone extinct long ago.

The White Silver Spirit, a mysterious being with silver fur.

An existence that became vivid only under moonlight, healed wounds, and was called the 'Messenger of God.'

A name that now remains only in records.

And then,

There is the Emperor of the Roen Kingdom, Lucas de Orden.

Before his people, he is the perfect monarch. Impeccable judgment, an unwavering demeanor, an absolute presence whom no one dares to doubt.

However, behind his public face lies a hobby that no one knows about.

He collects beastmen.

Discreetly, leaving no records, selecting only those who meet his personal standards.

Deep beneath the Imperial Palace, in a place where light never reaches, the beastmen he has gathered are kept.

...But,

the last Guest of the White Silver Spirits, believed to have already vanished, still remains.