Inumaru is a celestial being and a candidate in the tournament to determine the next god, serving as the partner to the middle schooler Seiichiro Sano. At twenty-eight years old, he has a calm and serious demeanor, often appearing polite, thoughtful, and somewhat reserved. Despite this composed exterior, he has an easily excitable and occasionally flustered side, particularly when confronted with the eccentricities or reckless actions of those around him. His hobbies include taking walks and basking in the sun, while he dislikes strenuous physical exercise due to his low stamina. He has a peculiar talent for splitting an apple with his bare hands.

The core of Inumaru's personality is a powerful and unwavering sense of justice, defined by his absolute unwillingness to ignore people in danger, regardless of the reason. This credo is what first led him to be paired with Sano, as he risked his own safety to help save a child from a burning building, mirroring Sano's own heroic actions. This selfless nature is his primary motivation, driving his actions throughout the tournament. He does not seek power for its own sake but acts out of a deep-seated need to protect others, even at great personal cost.

In the story, Inumaru initially appears in the background before approaching Kousuke Ueki with a desperate plea to save Sano. It is revealed that Sano had been forced to join the villainous Robert's Ten because the enemy, Karlpacchio, had attached a creature called a Death Pentagon to Inumaru's neck. This creature could be awakened at any moment to drain all of his blood, killing him instantly. To ensure Sano's compliance, Ueki's group was also threatened with poison bracelets. This hostage situation forces Sano into a battle where he cannot win or lose without sacrificing someone he cares about. Faced with this impossible choice, Inumaru makes a critical decision. Believing it is unacceptable for innocent people like the ordinary humans Ai Mori and Rinko Jerard to die because of him, he breaks the cardinal rule of the tournament. He gives his power to Ai Mori, a second person, knowing that this act will immediately condemn him to fall into Hell Prison as punishment. This self-sacrifice removes the leverage against Sano, freeing him from his obligation.

Inumaru's key relationships are central to his development. His bond with Seiichiro Sano is deep, blossoming from a formal partnership into a true friendship built on mutual respect and shared heroism. Sano thinks of Inumaru not just as a candidate but as a friend, and Inumaru's ultimate sacrifice is made specifically to save Sano and his companions. He is also familiar with Kobayashi, the celestial candidate for Ueki, and their relationship is one of long-standing acquaintance. While Kobayashi often teases or pranks him, Inumaru holds a degree of respect for him, though this is frequently tested by his companion's mischievous behavior.

Inumaru's development is marked by this profound act of self-sacrifice. He willingly sends himself to the harsh conditions of Hell Prison, enduring significant suffering for the sake of others. His time in prison, often in the company of Kobayashi, reveals his resilience and his continued concern for his friends on Earth. This ultimate sacrifice underscores his complete commitment to his moral code. Ultimately, his actions and selflessness leave such a lasting impression that after the tournament concludes, he is chosen by the team to become the next god.

Notable abilities are not the focus of Inumaru's character, as his strength lies in his moral conviction rather than combat prowess. As a celestial being, he can grant a unique power to a single human on Earth, which he does for Seiichiro Sano. He demonstrates no physical fighting abilities but possesses the willpower to break the tournament's most sacred law, fully accepting the terrifying consequences. One of his few displayed talents is the parlor trick of splitting an apple with his bare hands.