Higan, also known under the alias Joe Logan, is the central protagonist of the narrative. He is a former ninja, a classification known as a Nukenin, who made the choice to abandon his clan and its violent traditions to build a new life. He adopted a new identity and altered his facial features using a specialized masking system, seeking total anonymity to live peacefully in rural America with his wife, Mari, and their young son, Ren.

Higan is characterized by a stark duality that forms the core of his journey. Initially, he is a man who has successfully suppressed his lethal past, embodying the role of a husband and father in a quiet, domestic setting. However, the brutal murder of his family at the hands of his former clan shatters this peace, unleashing the persona of Ninja Kamui. This version of Higan is defined by an unbridled rage and a singular, bloodthirsty focus on vengeance. Over the course of his quest, this intense fury shows signs of diminishing, making way for a more complacent and less volatile individual, a shift that reflects the psychological toll of his mission.

Higan's primary motivation is revenge. He is driven by the need to hunt down and eliminate every member of the ninja organization that destroyed his family, operating on direct orders from their leader, Yamaji. While avenging his wife and son is the immediate catalyst, his actions are rooted in a deeper, more foundational break with his past. His exile was not a simple act of desertion but the culmination of a slow deprogramming process. He broke the clan’s strict ninja code, which demanded emotional detachment and complete subservience to the mission, by falling in love with his colleague, Mari. Choosing to protect her over following orders was the defining act that set him on this path.

In the story, Higan serves as the engine of the plot, a force of nature pitted against both ancient traditions and advanced technology. His quest pits his traditional shinobi skills against high-tech weaponry and combat cyborgs, as he works to dismantle the powerful clan and its corporate allies from the inside out. His key relationships are central to the drama. His wife, Mari, also a former ninja who was trained alongside him, was his partner in both love and the escape from their former life. His primary adversary is Zai, his former friend and ally. Their history of shared missions and camaraderie adds significant weight to their rivalry, as Zai remains bound by the code Higan rejected and is ordered to eliminate him. He also has a connection to his former master, Yamaji, the head ninja who now seeks his death.

Higan demonstrates notable development as a character. While the driving force of his arc is vengeance, his journey reveals a man who had already completed a major internal transformation before the story even begins. His decision to leave the clan was a conscious, deliberate choice to reject a dehumanizing code, showing a capacity for critical thought and emotional depth. As the narrative progresses, the all-consuming nature of his rage begins to subside, suggesting that the path of revenge is not a static state but an experience that changes him further.

In terms of abilities, Higan is an extraordinarily skilled warrior, having mastered countless fighting techniques during his time in the clan. His combat style is incredibly swift, and he demonstrates excellent proficiency with a blade, capable of taking on numerous opponents simultaneously. His most distinctive power is a secret ninja art known as the Secret Stark of Awareness, which manifests as a smoke-like ability. This power disorients his enemies and provides a significant boost to his own combat abilities. However, this technique carries a heavy risk, as its repeated use takes a massive toll on his body. This blend of ancient ninjutsu with a brutal, highly skilled physicality makes him a formidable opponent against both traditional assassins and technologically enhanced foes.