Sawako, a young girl devoted to her spirited puppy Koro, faces a fleeting lapse when she accidentally leaves the front gate unlatched before school, enabling Koro to wander into their suburban Tokyo neighborhood. Determined to reclaim her companion, she partners with her father to post "Lost" signs and comb the streets. In early scenes, she dons a blue dress layered over a beige-yellow shirt, accessorized with a pink bag and red rucksack, later exchanging it for a cheerful yellow dress upon reuniting with Koro.

Her name, woven from the Japanese characters for "help," "harmony," and "child," echoes her gentle nature. Mornings begin with affectionate rituals—tickling Koro’s belly before departing—underscoring their bond. His disappearance fractures this routine, leaving her visibly distraught. The collaborative search with her father illuminates both their familial solidarity and her resolve to mend the consequences of her oversight.