Yuuichi Momose and Sumi Fujino have been inseparable since early childhood, their families so close they are practically one unit. Now in high school, they remain classmates, but the carefree intimacy of their younger years has been replaced by a growing sense of distance and formality. Reaching puberty has made them acutely aware of each other in a new, awkward way, blurring the line between familiar comfort and romantic attraction. Although they know each other better than anyone else, a delicate tension now fills their interactions. The story follows their heart-pounding daily lives as they navigate this confusing shift, trying to determine if their relationship can ever evolve beyond just childhood friends. The narrative frequently contrasts present moments with flashback memories from their past, highlighting how their earlier innocent behavior compares to their current self-conscious feelings. One day, Sumi suddenly comes to Yuuichi's house, an event that begins to slowly rekindle the magic of their past connection and push them toward a new understanding of their bond. The manga maintains a wholesome, drama-light tone, focusing on the cute and awkward moments between the two protagonists as they rediscover the closeness they once took for granted.