Oxnard, alternatively known as Koushi-kun in Japanese, serves as Hamtaro's first and closest companion within the Hamtaro franchise. Their friendship began when Hamtaro moved to a new neighborhood and deepened through the parallel bond between their owners, Laura and Kana Iwata. Initially residing with Kana, Oxnard later relocates to live alongside Pepper on Dylan's farm. Physically, he is distinguished by his large size and gray-and-white spotted fur, reminiscent of a calf's pattern—a trait inspiring his Japanese name meaning "calf"—paired with bluish-gray eyes. He is rarely seen without his trademark sunflower seed, a favorite food whose loss visibly distresses him. His personality leans toward shyness and timidity; Oxnard is easily frightened, often reacting tearfully to perceived dangers. Boss frequently capitalizes on this fearfulness with light-based pranks. Despite his cowardly tendencies, Oxnard exhibits steadfast loyalty and surprising bravery when friends require aid, gradually evolving into a more dependable figure. An insatiable appetite, particularly for sunflower seeds, defines him, sometimes hindering adventures—exemplified by an incident where overeating candy inflated his belly like a balloon. He is also notably clumsy and runs slower than fellow hamsters. Yet his profound kindness and incapacity for malice solidify his role as a deeply caring friend. A significant story arc involves Oxnard's romantic relationship with Pepper. Initially concealed by his shyness, his feelings culminate in a long-distance confession during "Oxnard's Big Crush." Their dynamic features frequent arguments, quickly resolved, underpinned by mutual deep affection. Late in the series, Oxnard chooses to stay with Pepper at Dylan's farm rather than return with Kana. This relationship concludes with their marriage in the series finale, "Happy Ham-Ham Wedding!," where they invite all known Ham-Hams. Their pairing represents a childhood-friend romance, contrasting Pepper's adventurous, athletic spirit against Oxnard's sensitive, passive nature. Beyond Hamtaro and Pepper, Oxnard admires Boss, often seeking training to emulate his strength and bravery. His character journey—from a food-focused, hesitant hamster to a devoted partner and courageous friend—remains consistent throughout the anime, culminating in his marital commitment to Pepper.