Inukai Takeru is one of the male officers serving in the special division known as Tokko. His personal history is marked by tragedy, as he was recruited into this elite unit by his superior, Ryoko Ibuki, specifically after demons kidnapped his sister. Prior to joining the police force, Inukai was a martial artist, with his background heavily implying training in the practice of kendo.

In terms of personality, Inukai is a quiet and reserved individual, rarely speaking more than necessary. He is known for his typical attire, which consists of black clothing paired with black sunglasses, and he often wears a cross necklace. As a member of Tokko, Inukai is a Symbiont, a human who hosts one of 108 fragments from a device known as the Box of Dirge, which grants him the supernatural strength, speed, and resilience required to combat the demonic Phantoms that threaten humanity. His primary weapon in this fight is a large sword, which he wields with considerable skill. Within the group, he shares a significant connection as a long-time acquaintance of his colleague, Sakura Rokujo.

Inukais role in the story is that of a steadfast and experienced frontline fighter for Tokko. He is one of the first male officers to join the unit and serves alongside Sakura and another member named Kureha Suzuka under Ryoko Ibuki's command. His development and story arc conclude with his death in the ruins of the Machida apartment complex, the site of a past massacre central to the plot. There, he is killed by Sakura's younger brother, who has become possessed by a powerful Phantom spirit, in a confrontation that results in a double death for both combatants.