Harried production assistant Kishida Tomoya (Ichihara Hayato) spends most of his working hours making mistakes and being yelled at. Recalling his college days, he messages a picture of a rainbow to his longtime friend Aoi (Ueno Juri), only to find out later that she has passed away in a plane crash.
Tomoya and Aoi met in college, developing a close relationship that seemingly went beyond friendship, but neither ever voiced their true feelings to each other. Devastated by the news of her death, he thinks back to their days together, revisiting the love they never had.