Naoto Hachiouji, nicknamed "Senpai," begins as a deeply introverted high school student shaped by past bullying, which fuels his social anxiety and reliance on solitude. To shield himself, he cloaks his timid nature in indifference, avoiding eye contact and stifling emotions. Tall and slender with pale skin, curly brown hair, and horn-rimmed glasses—later replaced by contacts—his "fluffy," sheep-like appearance draws occasional teasing yet hints at an underlying handsomeness acknowledged by peers like Nagatoro.

Academically driven and artistically talented, he immerses himself in creating a fantasy manga starring Siegfried, a self-insert protagonist, and a knight modeled after the art club president. Early struggles with drawing female figures ease as he uses Nagatoro and her friends as muses, their likenesses gradually enriching his work. His dedication eventually secures him a place at Tokyo University of the Arts, a testament to his honed skills and burgeoning confidence.

Initially friendless, his life shifts through encounters with Nagatoro’s circle—Gamo-chan, Yoshi, and Sakura. Their teasing, though relentless, slowly chips away at his isolation, nurturing self-assurance. Nagatoro’s mockery softens into mutual affection, with Senpai defending her from detractors, confronting critics of her art, and ultimately confessing his love, solidifying their romance. His wary dynamic with her friends warms into camaraderie: Gamo-chan coins the nickname "Paisen," Yoshi delights in his tousled hair, and Sakura observes their bond with quiet amusement.

Growth manifests in newfound assertiveness. Passive acceptance turns to defiance—chiding Nagatoro’s harsh teasing, challenging classmates who belittle her—and emotional resilience, exemplified when mending their relationship after a dispute over a classmate’s nude portrait. Though privately drawn to fanservice, he maintains respectful boundaries, earning trust from Nagatoro’s friends. Nagatoro’s encouragement prods him beyond self-doubt—embodied by his mantra, "all I can do is draw"—toward physical activities and social engagements he once avoided.

After graduation, he relocates to Tokyo but stays tethered to Nagatoro, later inviting her to join him, a gesture cementing their enduring bond. His journey from a reclusive artist to a self-assured individual mirrors themes of transformation through unconventional yet steadfast connections.