Ryō Kutani is a student initially in the same academic year as Tamaki Kasuga and Takuma Onizaki, though he is one year older due to repeating a grade. His sporadic school attendance results in limited initial recognition from Tamaki. Ryō maintains a lone wolf persona, operating independently and pursuing his own investigations without external influence, which creates an intimidating presence among peers. He communicates directly and sometimes aggressively, openly expressing opinions that can provoke resentment. A notable behavior includes sniffing Tamaki, stemming from heightened olfactory senses due to his supernatural heritage.

He is the true heir of the Inukai clan, destined to be a Guardian for the Tamayori Princess. This status was concealed during his childhood by his mother, leading Shinji Inukai to initially assume the Guardian role. Upon revealing his identity and heritage, Ryō is formally accepted into the group of Guardians protecting Tamaki. His existence had remained hidden within the Inukai household until this disclosure.

As a descendant of an okami (wolf spirit), Ryō possesses supernatural abilities including enhanced smell and wolf-related powers. Accessing his full abilities alongside the other Guardians triggers a physical transformation manifesting wolf ears, a tail, and red markings around his yellow eyes and cheeks. His base appearance features shoulder-length olive (anime) or dark gray (game) hair and striking red eyes, contributing to an inhuman aura.

Ryō transitions from an isolated figure operating peripherally to an integrated Guardian. He collaborates with Masataka Ashiya, who is connected to a paranormal government agency. Across the series' events, particularly in the second season, Ryō embraces his role as a Guardian, aligning his actions with the group's mission to protect Tamaki and counter threats from the antagonistic organization Logos. This integration signifies his acceptance of the responsibilities tied to his bloodline and heritage.