Yamato Arima attends the same school as Nao Hatori but is assigned to a different class. Each morning, he walks his dog Hatsupi in a park regularly visited by Nao and her dog Chokotan. Nao quietly harbors feelings for him but wrestles with self-doubt, often freezing when opportunities to interact arise. Arima reciprocates her interest, strategically aligning their walking schedules to create chance meetings. Their exchanges remain brief and guarded, tempered by Nao’s timidity.

His presence subtly propels Nao’s attempts to confront her insecurities. In one pivotal moment, she bakes birthday treats for Hatsupi, hoping to bridge a connection with Arima. Yet when face-to-face, her nerves overwhelm her, and she flees—exposing the fragile push-pull between their mutual attraction and her anxiety. Later, spurred by Chokotan’s persistent nudging, Nao resolves to try again, though the results of her renewed effort remain untold.

The narrative does not elaborate on Arima’s personal history, family ties, physical traits, or potential story extensions beyond his role in this tentative relationship dynamic.