Kasumi is shocked to discover that her older sister's fiance is the man she first fell in love with five years ago in high school. At the time, he was her high school teacher and ultimately quit his job racked with guilt over their relationship. Kasumi was deeply hurt and struggled for a long time to overcome her sadness. Now the two of them must come to terms with their secret past before the ones they care about in the present are hurt.
Two kids meet near a floodgate after school. Yu is a shy 17 year old girl who sits down next to Yosuke as he plays his guitar. Yosuke recently gave up playing sports and has devoted himself to playing the guitar. He only plays a few lines over and over, as he tries to make a song from what he feels. Their relationship progresses tentatively as they both have difficulty in expressing their feelings and thoughts. One day Yu takes the initiative and kisses Yosuke. Yosuke responds by picking up his guitar and going home. Years later Yu wonders, "Why did I cry? Why didn't I stop crying? Why?"..while Yosuke wonders "Why did I run away from you that time?" Fast forward seventeen years later. They haven’t seen each since their days in high school and now have moved on with their separate and empty lives. That is until one day they randomly meet during an audition. They agree to go out together after work for drinks. As the evening turns into the early morning, they are still awake sharing memories of their high school days. After 17 years Yosuke finally kisses Yu. Yu starts to cry again and they soon go to visit her older sister. The next day Yosuke decides to call Yu and make good on a promise he made to her 17 years ago, that is he would play her his song when it is completed. Yu agrees to meet him again and Yosuke goes home to get his acoustic guitar. While on his way to meet Yu, fate deals a strange twist to their plans, perhaps this will be the moment where they can finally say “Sukida.”
