Ioryogi is a central figure who appears primarily in the form of a small, blue, dog-like plush toy with a red spiked collar. Despite this deceptively cute appearance, his personality is notably harsh, short-tempered, and often crude. He frequently berates his charge, Kobato, for her naivety and clumsy nature, going so far as to call her "Dobato," a nickname meaning "stupid dove". His features are known to twist into a horrifying expression when he is enraged, and he can produce a powerful fiery blast from his mouth, a force he often directs at annoyances or even at Kobato herself when she makes a mistake.

Ioryogi originates from a realm known as the Other World or Spirit World, where he belonged to a form of aristocracy and was a figure of significant importance and respect. His current stuffed animal form is a direct punishment for his past actions. Before the events of the story, he fell in love with an angel named Suishou and subsequently started a war against Heaven in an attempt to be with her, thereby breaking a non-aggression treaty between the worlds. As a consequence of losing this rebellion, he was transformed into a plush toy by a higher divine power and tasked with guiding Kobato on her mission to fill a special bottle with healed hearts.

His primary motivation throughout the story is intrinsically linked to this punishment. He must ensure Kobato succeeds in her mission within a set time limit, or he will lose the chance to ever return to his true form and his original world. While his initial desire to help Kobato is largely self-serving and focused on regaining his former body and powers, his attitude evolves over time. He becomes genuinely protective of her, offering gruff encouragement by patting her head and showing a willingness to sacrifice his own chance of redemption if it means her wish can be granted.

Ioryogi acts as Kobato's mentor, guide, and protector, possessing a strong dose of common sense that contrasts sharply with her naivety. His mission is to teach her how to function in the human world and help her identify and heal wounded hearts. He interacts with several other characters who share his predicament, including Ginsei, Genko the bear who runs a baumkuchen shop, and Zuisho, all of whom are also trapped in animal-like forms as a result of their involvement in the war with Heaven. His most significant relationship, however, is with the angel Suishou, the being for whom he started the war. It is revealed that Suishou shares a soul with Kobato and resides within her, making Ioryogi's bond with Kobato even more complex.

Throughout the narrative, Ioryogi demonstrates notable development. He begins as a purely cynical and ill-tempered creature but gradually reveals a softer, more caring side. His time with Kobato teaches him patience and the value of waiting and caring for another person. In his true form, glimpsed only in shadows, he appears as a tall man with long black hair, markings under his eyes, and a long cape, a stark contrast to his plush toy disguise.