Giiru is a central supporting character from the anime Cerberus, known primarily for his role as the adoptive father and devoted guardian of the protagonist, Hiiro. His identity is that of a half-blood, born to an ogre father and a human mother, which places him in a unique and often challenging social position within the world's fantasy setting.

The character's background is defined by profound personal tragedy. Before the events of the story, Giiru's mother was pursued by humans, leading to a massive hunt that caused devastating losses within the ogre clan. In an effort to place blame for this catastrophe, Giiru's own parents—his ogre father and human mother—were captured and executed by the very ogres they belonged to. This traumatic event left a deep scar on Giiru and shapes much of his worldview. Before becoming Hiiro's caretaker, Giiru served as a retainer to Hiiro's biological parents, Bairo and Kissmitete.

His personal philosophy is guided by the last words of his father, who told him that not acting in the face of injustice is an act of cowardice. Giiru takes this principle to heart, training diligently every day to ensure he has the strength to protect those who are precious to him. This strong sense of justice and his protective nature drive his actions throughout the series.

Following the tragic failure of the ritual to seal the evil dragon Daganzord, an event known as the Balbagoa Tragedy, Giiru rescued the young Hiiro. He made the decision to raise the boy as his own son, taking on the roles of both a butler-like caretaker and a stern father figure. He was also the first to recognize Hiiro's natural talent as a mage, showing his perceptive nature. Giiru is a skilled cook and a proficient swordsman, having trained Hiiro in the use of his giant blade to seek revenge against the dragon.

In his role within the story, Giiru acts as a steadfast anchor for Hiiro. While he is a capable fighter, his primary function is that of a mentor and a loyal guardian. When Hiiro runs away from home on his own, Giiru immediately goes in search of him, accompanied by the small dragon-like creature Palpa. Upon reuniting with Hiiro, Giiru chooses to accompany him on his dangerous journey, providing support, guidance, and protection.

His key relationships include his deep bond with his adopted son, Hiiro. He is fiercely devoted to the boy, driven by his promise to protect what matters most. He also shares a close alliance with Palpa, as the two search for Hiiro together and serve as his primary companions. His past as a servant to Bairo and Kissmitete ties him directly to the central tragedy that motivates the plot.

Regarding character development, Giiru's stoic and reliable nature is tested by his traumatic past. During the journey, the group encounters situations that remind him of his parents' death, forcing him to confront his grief and further solidifying his resolve to prevent such injustices from happening again. His development is more about reinforcing his existing virtues of loyalty and courage than about changing his fundamental personality. He consistently stands by Hiiro, even when the young hero begins to lose control of his dragon powers, once being slashed by Hiiro during such an episode.