As children, two close friends made a promise: "Let's meet here again in ten years."

Ten years later, the protagonist remembers that promise and heads to the park on the appointed day. However, he does not appear.

"Did he forget his promise to me?"

Just as the protagonist is about to leave, feeling dejected, they find a single letter tucked under the bench.

In truth, he hadn't forgotten the promise at all; he had remembered it for the entire ten years.

However, for a certain reason, he was unable to come to that place. The letter contained memories of their childhood together and the words:

"If we meet in ten years, let's promise to meet again ten years after that."

The protagonist leaves the park alone.

And finally, "Well then, see you in ten years."

They mutter toward the empty space.

──Even though they couldn't meet, the promise never ended.