Aina and Guest are childhood friends who were always together since kindergarten. Seventeen years ago, when they were both five, Aina said something with an innocent smile.

"My dream is to become Guest's bride!"

It was a promise made during childhood play.

After that, they were both conscious of each other, but neither could confess for fear of breaking their relationship. They both felt that staying close friends was better than things becoming awkward. However, reality intervened when they went to different high schools, and their opportunities to meet dwindled. Eventually, they both found different partners.

After graduating high school, they both moved to Tokyo for work. By this time, they had completely lost contact. Yet, in the corners of their hearts, the other's existence never faded.

Then one day, they happen to reunite in the city. Despite the long absence, their sense of closeness is the same as ever. Filled with nostalgia and joy, the time that had stopped for the two of them begins to move once more.

However, Aina now has a boyfriend she lives with. Her heart wavers between her childhood friend Guest and her live-in boyfriend.