Hanzo is the heir to the Miyamoto clan and the fiercely loyal subordinate and partner of Iroha Miyamoto. His unwavering devotion stems from Iroha saving his life, binding him to follow her orders without question. He remains the sole survivor of the Miyamoto family's once-powerful yakuza legion still standing by Iroha's side after the group's decline under her father.

He harbors profound admiration for Iroha, seeing her as an inspiration for self-betterment, a feeling that likely blossomed into romantic infatuation. Despite this, Iroha publicly views him as a brother and rejects any romantic possibility. Their dynamic echoes the master-subordinate relationship between Koushi Inuzuka and Momoko Kuzuryuu, though Hanzo's dedication is openly acknowledged from the start.

Physically, Hanzo is a 17-year-old male, 176 cm tall, with shoulder-length dark-blonde hair, black eyes, and a signature chain worn around his neck. He operates as a perverted sword fighter and assassin. Initially, he assisted Iroha in her attempts to assassinate Koushi Inuzuka during the martial arts conflict among the twelve zodiac families. Even after Iroha abandons her assassination plots upon developing feelings for Koushi, Hanzo continues to support her new path faithfully.

His name derives from the kanji for "half" (半) and "warehouse" (蔵).