Koyuki Hikawa is a reserved, introspective high school student marked by her constant self-doubt and tendency to overthink every interaction. Haunted by past relationships and the weight of her own expectations, she often erects emotional walls—rejecting others before giving them a chance to truly understand her. Over time, she yearns to break free from her self-imposed isolation and embrace a more genuine, open connection with those around her. Her journey is one of learning to trust both herself and the kindness of others, even when vulnerability seems daunting.