Nezumi is the closest companion to the protagonist crocodile, their friendship anchoring the narrative's central relationship. He shares mundane daily experiences with the crocodile, including part-time work routines, ramen shop visits, basketball games, video gaming, and movie watching. These ordinary moments define their bond before the crocodile's predetermined fate. During the crocodile's hospitalization, Nezumi visits and attempts to uplift him by recounting his favorite jokes, demonstrating steadfast loyalty. Roughly 100 days before the crocodile's death in cherry blossom season, Nezumi grows concerned when the crocodile misses their planned meeting. He searches by motorcycle, locates his friend, and photographs the cherry blossoms to share—images the crocodile never receives.

After the crocodile's death, Nezumi and their mutual friends grapple with grief. Shared memories become emotionally fraught, causing communication to dwindle and the group to gradually drift apart. The cherry blossoms from their final intended outing later become obscured by foliage, their fallen petals altered by rain, symbolizing irreversible time and absence. Nezumi's arc reflects loss's impact on human connections and memory's quiet endurance in daily life after tragedy.