Shisuto Naruse is a first-year student at Itan Private High School who emerges during the second semester. His name puns on "narcissist," reflecting his core trait. He possesses pale skin, short turquoise or blue hair sculpted with gel, and rimless glasses, frequently seen with earbuds and his school jacket unbuttoned. Though slim and muscular, he exhibits extreme physical clumsiness and harbors intense fears of insects, ghosts, heights, and water. Academically exceptional, his high exam scores surprise peers. His ambition is to become Japan's Prime Minister. At home, his family, particularly a similarly narcissistic grandfather, witnesses a quieter, more well-behaved side. He relaxes by gazing into mirrors and enjoys Western pop music, notably an artist parodying Justin Bieber called "Justice Bieber." Naruse firmly believes himself the "handsome protagonist" of his life, assuming everyone secretly admires him but feels unworthy to interact. This delusion extends to Shoko Komi, whom he considers his only aesthetically equal peer. He correctly deduces her social anxiety but dismisses it, theorizing she merely awaits others' approach. His attempts to connect are repeatedly thwarted by protective classmates like Ren Yamai. When Komi returns a dropped handkerchief, he misinterprets it as romantic interest and unsuccessfully seeks her phone number. Encouraged by his friend Chuusaku Kometani, who provides dry commentary on his delusions, Naruse befriends Hitohito Tadano instead, exchanging numbers and regularly sending him selfies. He occupies the back-row window seat, referencing the "Protagonist's Seat" anime trope. His development intensifies during group activities like a school trip where he bonds with Makoto Katai. In his second year, sharing a class with Komi, Tadano, and others, he integrates into their circle. A pivotal beach trip sees him trip and swept out to sea upside down, requiring lifeguard rescue. Ase Shibuki stays with him afterward, marking their connection's start. During a test of courage, Naruse initially hides behind Ase due to his horror fear but later comforts her when she apologizes for nervous sweating, thanking her for her support post-rescue and listing her positive qualities. Masking this sincerity with narcissism, he begins developing genuine feelings. Subsequent attempts to assist Ase—fetching water during a sports festival or helping clean confetti—are interrupted by Kiyoko Isagi physically blocking his advances. Naruse and Ase's relationship progresses through summer festivals and skiing trips, where he shows chivalry like offering his arm for support. Their frequent proximity prompts classmates like Rumiko Manbagi to question their status. Ase later confirms they are dating, revealing she confessed during a video call where Naruse blushed with uncharacteristic vulnerability. Tadano inadvertently reveals their relationship publicly in class. Despite ongoing narcissism, Naruse demonstrates consistent kindness, never belittling others, and his support for Ase highlights his capacity for growth. He participates in school events like cultural festivals and shopping trips, often resulting in comedic mishaps. He ranked 25th in the series' popularity poll and appeared in background art as early as Chapter 17. While his narcissism contrasts with Ren Yamai's clinically concerning traits—lacking empathy, entitlement, and manipulation—Naruse's behavior remains comparatively superficial and non-malicious. Kometani summarizes him as "not a bad person."