Hachi, a black-and-white tuxedo cat, is the younger sibling of Haru, a stray adopted by protagonist Subaru Mikazuki. Rescued from the streets by pet store clerk Nana Ōkami, he transitioned into her care, distinguished by his unique facial markings—white fur that stops short of his eyes—and the absence of a collar unlike his brother.

Once struggling as a stray, Hachi’s early hardships mirror those of his siblings. Under Nana’s guardianship, he adapted to domestic life, joining her other cat, Roku. Though his interactions are sparingly depicted, they reinforce his identity as an animal given a second chance.

His bond with Haru persists as a testament to their shared origins, though their lives diverge: Haru remains pivotal to Subaru’s journey, while Hachi’s story spotlights the quiet fulfillment of safety and routine with Nana. His existence subtly emphasizes the series’ theme of compassionate intervention in the lives of vulnerable strays.

Documented material does not elaborate on Hachi’s personality traits, future arcs, or deeper narrative involvement beyond his adoption. He remains a steady, secondary figure symbolizing the quieter yet vital companionship animals provide within the human-centric world.