Atsuhiro Kagari, universally known as Akkun, exhibits extreme tsundere tendencies. Externally harsh and verbally abusive toward his girlfriend Non Katagiri—whom he calls Nontan—he hurls insults to conceal profound embarrassment over affection. This clashes violently with his internal reality: an obsessive infatuation where he privately reveres Non as angelic perfection.

His genuine devotion fuels disturbing behaviors: covertly stalking Non, taking unauthorized photographs, recording her voice, and plastering his bedroom walls and ceiling with her images. He meticulously documents minutiae like her average chews per bite. Non, however, interprets these acts as charming quirks rather than red flags.

Their history traces to middle school, where they began dating and exchanged nicknames. Akkun’s photo obsession ignited when Non’s mother gifted him his first picture of her, spiraling into his clandestine archive. His family includes parents Keita and Sakurako Kagari, plus younger sister Chiho—who shares his tsundere traits but openly showers Non with affection.

Akkun battles crippling embarrassment in expressing love. Simple gestures like hugging or kissing trigger days of avoidance. A recurring struggle is his inability to say Non’s first name without blushing or fleeing—a hurdle confronted in the series’ finale. His incremental growth includes tolerating fleeting touches and once texting "I love you" when speech failed.

Beyond Non, he maintains a close friendship with Masago Matsuo, a serious gamer who frequents Akkun’s home for dating sim sessions, irritating Chiho. He navigates peripheral dynamics with classmates like airheaded Konagi Irie and weary teacher Takumi Kubomura, though these remain secondary to his romantic turmoil.

Personality frameworks define him as an ISTJ—meticulous, rule-bound, emotionally restrained—and an Enneagram Type 1 Perfectionist, driven by rigid self-standards and criticism of perceived flaws. This fuels his conflict between idealized love and abrasive actions.