Jin, also known as Jin Kagemori, is a prominent supporting character in Daemons of the Shadow Realm. He is introduced as a member of the Kagemori household, a powerful underground clan. Specifically, Jin holds the position of the family's third son, a role that comes with significant responsibility. He heads the family's operational division and serves as its designated "cleaner," a euphemism for the agent tasked with carrying out assassinations and handling the subsequent disposal of bodies. Despite this grim profession, his portrayal is not that of a simple thug; his conduct is described as carrying the distinct air of an "intellectual gangster".

In terms of personality, Jin is consistently composed and unflappable. He is driven by reason rather than emotion, and his demeanor is straightforward and grounded. He maintains a refined appearance and a perpetually expressionless face, which adds to his air of detached professionalism. This calm and calculating nature is a key part of his character, as he appears to be the sort of person who thinks several steps ahead, which makes his intentions difficult to immediately discern. Among the members of the Kagemori family, he is noted to be comparatively honest and dependable, even though his daily work involves handling a wide range of tedious and dark affairs for the clan. His actions are not driven by cruelty but by a cold sense of duty, as seen when he is dispatched to capture the protagonist, Yuru.

Jin's primary role in the story is that of an agent for the Kagemori clan, tasked with confronting and capturing Yuru. He acts as a direct obstacle and a significant point of contact between Yuru and the mysterious organization that has upended his life. His mission brings him into direct conflict with Yuru, whom he is ordered to find. To accomplish this, Jin demonstrates a tactical mind, using a vial of the blood of Yuru's twin sister, Asa, to bait a trap. He correctly anticipates that Yuru would use the unique bond of shared blood to track her, showcasing his strategic thinking. When the trap is sprung, Jin admits personal responsibility for the attack on Yuru's village, confirming his role in the violence that set the story in motion.

His key relationships are primarily defined by his duties. He is a trusted agent of the Kagemori leadership and is often seen receiving orders from the clan's elder. His dynamic with Yuru is the most developed in the early narrative, evolving from that of hunter and prey to a more complex standoff. After Yuru turns the tables and captures him, Jin shows no fear, calmly confirming his role in the village's destruction. Yuru, however, chooses not to kill him for revenge, instead demanding that Jin facilitate a meeting with Asa. This interaction highlights Jin's role as a crucial link in the chain of mysteries surrounding the Kagemori family. Later, his tense relationship with other members of the family is shown, as he and Asa are visibly unhappy about the presence of a mysterious, unnamed man from their own clan.

As a character, Jin does not undergo a significant transformation in his early appearances, but his role in the plot develops. He begins as a shadowy enforcer and becomes a captured source of information, forcing a direct confrontation between the protagonist and the main antagonists. His abilities are noteworthy and integral to his role. Jin is a Messenger User, meaning he can contract and command supernatural beings. His contracted Messengers are a unique pair of anglerfish-type Daemons named Ai and Makoto. These Daemons grant him formidable and gruesome capabilities. Ai is capable of swallowing targets or debris whole, effectively acting as a tool for capture or disposal. Makoto, on the other hand, can open up to produce a veritable arsenal of weapons, including swords, shotguns, and rocket launchers. This combination of powers makes Jin an exceptionally dangerous and versatile opponent, suited for both stealthy assassinations and direct confrontations. His controlled and calculating personality is also reflected in his strategic use of these Daemons, such as using Ai to trap Yuru in a cage of teeth while using a vial of blood as bait.