Amari is a member of the D-Agency, an elite spy organization, and is considered one of the oldest members of the group alongside Kaminaga. Physically, he is an adult male with brown eyes and brown hair cut to ear length, standing approximately 175 centimeters tall. His appearance is often described as having an amiable baby face, which can sometimes hide a deeper, more world-weary quality.

In terms of personality, Amari is notably sociable and independent, with a reputation for being charming and easygoing. He is not overly concerned with minor details and is viewed by his peers as a protective, older brother figure, reflecting his caring and dependable nature. His skillset aligns with his personality, as he is specifically utilized for handling situations that involve women and requires a personable agent.

His role within the story is demonstrated during a mission on a civilian steamship traveling from San Francisco to Tokyo. Tasked with hunting a British MI5 officer and encryption expert who is traveling under an alias, Amari relies on his keen observational skills and intellect. He is able to identify his target despite the man having undergone extensive plastic surgery, using a combination of unalterable physical traits and a custom crossword puzzle to confirm his identity. This specific mission highlights his ability to operate in confined, public spaces and adapt to unexpected complications, such as the presence of another person hunting the same target for personal revenge. Information regarding his personal motivations, overall character development throughout the series, and detailed relationships beyond his general role as a senior agent remains limited.