Kantaro Ichinomiya is the main protagonist of the series, a professional folklore writer and a part-time exorcist active during Japan's Meiji era. He is a young man with a distinctive appearance, characterized by his albinism which gives him very pale skin, light hair that ranges from blond to near-white, and red eyes. His appearance is misleading, as he looks to be in his late teens or early twenties, but he is actually much older, giving him a level of experience and knowledge that his youthful face may not initially suggest.

Born with an extraordinary ability to see and communicate with youkai, or goblins, Kantaro was ostracized and bullied by other humans during his childhood. As a result of this isolation, his only friends were the youkai, and from them he developed a deep and genuine affinity for the supernatural world. His personality is complex, presenting a mask of shallow and materialistic traits to the world. He is frequently portrayed as greedy, constantly discussing fees and trying to get the most money out of his clients, and exceptionally lazy, often avoiding his writing deadlines and leaving chores to others, much to the dismay of his editor. He enjoys following trends and flirting with wealthy women, but these actions are largely a front for a more thoughtful and serious individual.

Beneath his immature and selfish exterior lies a deeply compassionate and tragic person. He holds a strong sense of spiritual balance and possesses a profound empathy for youkai, preferring to reason with them and help them rather than destroy them, which is the customary approach for an exorcist. This unique perspective stems from his own painful past, including a deep-seated resentment towards his absent mother and the emotional scars of a lonely childhood in which he was treated as a tool for his spiritual powers. His primary motivation is not to vanquish demons but to befriend them. From a young age, he was determined to find the legendary demon-eating tengu, believing that together they could become stronger and save each other from their respective fates.

In his search for the tengu, Kantaro travels the countryside investigating supernatural occurrences. His life changes forever when he discovers the shrine where the powerful tengu is sealed. By releasing the creature and giving it the name Haruka, Kantaro becomes its master, as a named demon is bound by a name contract to the human who named it. This contract forms the central relationship of Kantaro's life, and his feelings for Haruka become a powerful emotional bond that guides his actions throughout the story. He lives with Haruka and a fox demon named Yoko, whom he also named, and who acts as a resentful but loyal housemaid. Other important relationships include his editor Reiko, who constantly pressures him for manuscripts, the young heiress Suzu Edogawa who has a crush on Haruka, and Sugino and Muu-chan, a married couple of goblins who become good friends and allies.

Throughout the series, Kantaro faces challenges to his relationship with Haruka, particularly from the antagonist Raiko Minamoto, who schemes to break their name contract and force Haruka to awaken his true powers and regain his lost memories. These events test Kantaro's resolve, forcing him to confront the depth of his feelings and his desire to protect Haruka above all else, revealing the serious and devoted person hidden beneath his lazy demeanor. His development centers on moving beyond the emotional isolation of his past and fighting to preserve the bonds he has formed with his supernatural companions.

Kantaro possesses notable spiritual abilities. His most significant power is the ability to name youkai, which creates a binding contract that makes him their master. He is a highly intelligent tactician, able to anticipate situations and manipulate events and people to achieve his goals, a trait that gives the series its title. His sixth sense is exceptionally powerful, to the point where he is sometimes considered more like a youkai than a human. He is skilled in both Shingon Buddhism and Shinto practices, allowing him to perform exorcisms and rituals, and he can function as a priest for various ceremonies. However, despite his power, he prefers to resolve conflicts through peaceful and reasoned means rather than brute force, always seeking to understand the youkai's perspective.