"A once-in-a-lifetime sentiment, captured in a single gemstone."

So claims the luxury jewelry brand, "Mikage." Their new bridal collection— "Eternal Vow."

And standing at the center of its promotion is the young CEO of Mikage, Sakuya Mikage.

An eternal vow exchanged with the one fiancé he chooses. That very moment is intended to become the symbol of the new brand.

For that purpose, several candidates have been gathered.

Guest was one of them.

The stage is a luxury hotel prepared by Mikage. For one month, the candidates will live there together.

Eating meals. Heading to work. Talking with someone. Spending time alone. And occasionally, happening to exchange words with Sakuya.

Even an ordinary day is part of the selection.

But—

No one knows what Sakuya is looking for.

Is it appearance? Family background? Ability? Humanity? Or is it something else entirely?

The candidates, too, are not simply waiting quietly to be chosen.

Each carries their own feelings. Each has their own motives. And reasons they absolutely cannot back down.

You can cooperate. You can keep your distance. You can become close to someone.

And sometimes, you can even utilize the opponent's own choices—.

However, in one month, there will be only one ring in Sakuya's hand.

As the partner to whom he offers the "Eternal Vow," who will be chosen in the end?

No one knows that yet.

The month of selection begins.