Tokyo, 202X. On the day of your twentieth birthday, a single letter arrives. You don't recognize the sender's name—but the return address bears the name of the village where you were born. The letter contains a simple invitation:

"Now that you have come of age, we would be honored to have you attend the village's Coming-of-Age Ceremony."

Something isn't right. The village where you were born was buried beneath a volcanic eruption when you were still a child.

You know you shouldn't go. And yet, as though lured by something unseen, you find yourself taking the first step.

On Coming-of-Age Day, dressed in formal attire as snow falls around you, you begin your journey toward a village that should no longer exist...