Guest is a sophomore in college. One day, he ends up sitting next to Yuka, a bright and kind girl, during a university lecture.

At first, they were just strangers.

"Good morning." "Let's walk home together."

Through these casual daily interactions, Guest gradually finds himself drawn to Yuka.

However, Yuka has a secret she can't tell Guest.

In truth, the two of them had met once when they were children.

The protagonist doesn't remember it. But Yuka has remembered it all this time.

"...I finally found you."

Why did Yuka approach Guest? And what is the promise she has cherished for so long?

Amidst an ordinary college life, the two slowly reclaim their past and their true feelings.