Hajime Kudō is a 34-year-old real estate agent who works at the Wang Lai Real Estate agency within the recreated Kowloon Walled City. He possesses a robust, lean build, with short black hair and black eyes, and is typically dressed in professional attire like a shirt and tie, though he often appears with his tie loose and shirt untucked. On the surface, Kudō comes across as careless, hot-headed, aggressive, and sometimes ignorant. However, this exterior masks a fundamentally kind, considerate, and sympathetic core. One of his notable personal quirks is a habit of touching the number eight whenever he sees it, believing it brings luck.

Kudō has a deep and abiding appreciation for the nostalgic atmosphere, urban culture, and cuisine of Kowloon Walled City. He cherishes its unchanging, retro quality, which often puts him at odds with his coworker, Reiko Kujirai, who is more open to modernity and new experiences. This preference for the old over the new is a defining aspect of his personality and shapes his worldview.

His past is complex and deeply tragic. Kudō originally transferred from a Japanese branch to work alongside the original Reiko Kujirai, often referred to as Kujirai B. She was his senior and mentor, and their professional bond eventually evolved into a romance and engagement. Kujirai B's death by a sleeping pill overdose, which is implied to be a suicide, devastated him. Following her death, Kudō became responsible for the creation of the current "Second Kowloon," a painstakingly detailed reconstruction based entirely on his own memories of the original city and his time with Kujirai B.

This unresolved grief profoundly influences his relationship with the current Reiko Kujirai, who is a copy or "generic" of his late fiancée. While Reiko A resembles Kujirai B physically, she lacks their shared memories and possesses contrasting traits, being more reserved and curious about new things. Kudō initially responds to Reiko A with icy dismissal, interpreting her actions as mimicry. When she confesses her romantic feelings for him, he explicitly rejects her by stating those feelings are "not real". Despite this, a strong and complex dynamic exists between them, described as fun and sibling-like, though he can also be cold due to the painful memories she evokes.

Kudō's internal conflict is constant, caught between honoring Kujirai B's legacy and accepting Reiko A's individuality. He frequently adopts Kujirai B's catchphrases, habits, and philosophies, demonstrating her pervasive influence on his identity. His subconscious attachment to the past is so powerful that it manifests physically, causing earthquakes within Kowloon during his nightmares. The story shows his struggle to let go of nostalgia, as his affection for Reiko grows only when she acts as her own person, yet he still retreats emotionally when triggered by memories of the original.

Kudō's key relationships extend beyond Reiko. He shares a close friendship with Gwen Tao, who is one of the few people privy to the truth about Kujirai B's death and the artificial nature of Kowloon. He harbors animosity and distrust towards Miyuki Hebinuma, especially after witnessing him kiss Reiko A. He maintains a friendly, sibling-like rapport with the part-time worker Xiaohei but dislikes Lin Yaomay due to her consistently aggressive and confrontational attitude towards him. Throughout the series, Kudō's journey reflects the painful struggle to reconcile the comfort of nostalgia with the realities of the present, as he lives within an imperfect replica of the past that cannot truly restore what was lost.