Hakubo revolves around the daily life of Sachi Koyama, a high school violinist with promising talent. Although Sachi is content with her school life and retains friends within the music club, her favorite pastime is appreciating the scenery around her neighborhood in Iwaki, Fukushima while walking to her bus stop alone.

However, during one of Sachi's after-school walks, she has an unexpected meeting with Yuusuke Kijinami, a boy whom she often notices on her bus ride home. After offering to help Kijinami find a perfect view of the evening landscape—the subject of his next painting for his art club's exhibition—the two forge a bond over their mutual admiration of the beautiful scenery bathed in sunset. This chance encounter brings together these two souls who yearn to cherish the present, knowing full well how easily it can all slip away.