The character is formally known as Baron Humbert von Gikkingen, though most refer to him simply as the Baron. He is not a biological cat but a living statue of an anthropomorphic feline, always dressed impeccably in a tailcoat, top hat, and carrying a cane, which gives him the appearance of a refined gentleman from a bygone era. His origin lies in the human world, where he was crafted as a decorative figurine and belonged to the owner of an antique shop. It is explained that statues like him come to life through the power of love and the dedication of their creator, allowing him to move and think of his own accord, particularly within the context of the fantastical events he becomes involved in.

In terms of personality, the Baron is defined by his unshakable dignity, politeness, and composure. Even in the midst of chaotic or dangerous situations, he remains calm and courteous, never losing his gentlemanly demeanor. He is wise and serves as a mentor figure, offering guidance that is both practical and philosophical. He is also brave and highly competent, never hesitating to take action when someone needs his help.

The Baron's primary motivation is to assist those who are lost or in trouble. He operates the Cat Bureau, a small, almost hidden agency dedicated to helping those who find themselves entangled with the affairs of the Cat Kingdom. His central goal in the story is to aid the young heroine, Haru, after she is whisked away to the Cat Kingdom and begins transforming into a cat against her will. He believes strongly in the importance of being true to oneself, and his main purpose is to help Haru rediscover her own identity and inner strength before she loses her human self entirely.

Within the narrative, the Baron acts as the leader of a small trio that includes Muta, a large, cynical, and gluttonous cat, and Toto, a sharp-witted raven who is also a living statue. While Muta often grumbles and Toto provides dry commentary, the Baron is the calm center of the group, coordinating their efforts to rescue Haru. His relationship with Haru is central to the story; he acts as her protector, guide, and an inspiration. He helps her navigate the dangers of the Cat Kingdom, and she, in turn, develops a deep affection for him, learning to be more confident and assertive from his example. His relationship with Muta is that of a long-standing partnership; the Baron patiently tolerates Muta's foul moods and laziness, often bribing him with food to secure his cooperation.

As a character, the Baron does not undergo a significant personal transformation, as he is already a complete and wise figure. Instead, his role is to be a catalyst for change in others, particularly Haru. He remains a steadfast and constant presence throughout the story, representing an ideal of courage, elegance, and integrity. His development is more about revealing the depth of his abilities and his unwavering commitment to his principles rather than changing his personality.

The Baron possesses several notable abilities. He is a highly skilled fighter and an expert swordsman, capable of disarming and defeating multiple armed opponents with nothing but his cane. His speed and precision in combat are formidable, allowing him to perform feats such as cutting the jewels from the Cat King's crown in a single, swift motion. Beyond his physical prowess, he seems to be immune to the magical rules of the Cat Kingdom, as he does not begin to transform into a cat like Haru does. His presence is also said to be a great threat to the kingdom itself, implying a hidden power that goes beyond his sword fighting. As an artificial being brought to life, he can also pronounce sounds that ordinary cats cannot, further distinguishing him from the feline inhabitants of the other world.