Boss is a self-proclaimed leader of the Ham-Ham gang, a title he carries with a mix of gruff pride and earnest responsibility. He is a field hamster, meaning he is not a pet like most of his friends, and he lives on his own in an elaborate burrow that serves as the main gathering place, known as the Ham-Ham Clubhouse. His physical appearance is distinct; he is notably the tallest of the group at twelve centimeters, with a large cream and brown coat, dark green eyes, and a dark brown patch of fur around his mouth and nose that resembles a beard. He almost always wears a signature yellow helmet and carries a small shovel, tools that reflect his hardworking and practical nature. A small, distinguishing nick is present in one of his ears.

Boss’s personality is a mixture of toughness and hidden sweetness. He often acts as if he knows everything, but this bravado frequently backfires in a humorous way, revealing a more awkward and unsure side. He has a short temper, yet he is considered to be extremely dependable, courageous, and kind-hearted. He would willingly give his own helmet and shovel to a friend in need, demonstrating that his leadership is rooted in genuine care rather than a simple desire for power. Because of his origins as a wild field hamster, he is more independent and familiar with nature than the other hamsters. He has developed a special instinct that can predict the weather, though he is ironically very prone to seasickness. He is also quite shy, a trait that becomes most apparent around certain female characters.

One of Boss’s primary drives is his long-standing, unrequited crush on Bijou, a pretty and refined hamster from Paris. He often goes to great lengths to impress her or win her affection, though his efforts are usually unsuccessful as Bijou sees him as more of a brotherly figure and does not reciprocate his romantic feelings. This crush drives much of his early behavior, though he later finds his attention wandering to other female characters. He develops a brief but exciting mutual affection with Gelato, a playful hamster who calls him her prince, which makes him very upset when she leaves. He also has a complicated admiration for Sabu, a rougher, more experienced hamster whom Boss sees as a mentor and a symbol of a "real man," to the point of once wanting to run away and travel with him.

His role in the story is central as the leader and owner of the clubhouse, which serves as the main setting for the Ham-Hams' adventures. He is a good friend and a mentor to Hamtaro, the hero of the group, who looks up to him for his wisdom and experience. Despite his tough exterior, he secretly values companionship highly, which is partly why he is always willing to host the other hamsters at his home. He holds a special fondness for Snoozer, a mysterious hamster who sleeps in a sock in the clubhouse, as Snoozer is often his only company when the others leave.

Boss undergoes subtle but notable development throughout the series. At one point, he decides to leave on a long journey, leading to the clubhouse being closed and the remaining Ham-Hams finding a new location called Sweet Paradise. Upon his return, he adopts a secret persona known as Hero-Ham, a masked and heroic figure who helps the other Ham-Hams without revealing his true identity. This act lasts for a while until Hamtaro eventually sees through the disguise, after which Boss returns to the clubhouse, though he occasionally dons the Hero-Ham outfit again to quietly assist others, especially those who do not know his secret. Beyond his leadership, his notable abilities include his expert digging skills with his shovel, his practical knowledge of nature and survival from being a field hamster, and his aptitude for building and maintaining the extensive tunnels that make up the clubhouse.