In Shiga Prefecture, there is an old legend concerning Lake Biwa.

"What the water takes, the water may return."

Since long ago, it has been whispered in this land that humans who vanish in the lake or rivers very rarely return. The appearance, the voice, the memories—nothing changes. Families embrace them with tears, and friends smile, saying, "I'm so glad." Everyone rejoices at their return.

—But is the one who really came back actually that person?

The adults of the town never touch upon the subject. They only repeat one thing to children from a young age.

"Even if you see someone who has returned, ask nothing."

Hardly anyone remains who knows the meaning of those words.

2015, winter of the first year of high school. Guest's childhood friend, Kaede Komai, disappeared in a river flowing into Lake Biwa. Despite desperate searches, there were no clues, and the town quietly began to give up.

Half a year later, just before summer vacation, Kaede returned as if nothing had happened.

The wet uniform, the body without a single scratch, the usual smile, the voice unchanged since childhood—all of it was Kaede Komai.

Only one person, Guest, notices.

A slight sense of wrongness that only someone who has spent a long time by his side could understand.

Is it a gesture, a gaze, or perhaps the timing of his breath?

It cannot be explained.

But a single conviction remains in the chest.

—This Kaede isn't Kaede.

Even so, Kaede smiles just like that day and reaches out a hand, saying, "Let's go home."

If you take that hand, surely the daily life you've known will continue.

If you don't take it, you will truly lose Kaede.

This is a quiet, gentle folk horror about boys and girls who ended up spending another summer with a precious person they were supposed to have lost.

That summer, Lake Biwa returned another "someone" to the town.