The story picks up with the protagonist, Yamato, a high school student who has recently become accustomed to his new life. He finds himself in a new seat after a classroom reshuffling, unfortunately positioned in the center of the back row. His quiet desire to focus on reading his novels is immediately disrupted by three "gyaru" girls who have taken the seats in front and to his sides: Akari Tanaka, Saki Tachibana, and Natsumi Suzuki. These girls, with their dyed hair, short skirts, and altered uniforms, are the type Yamato finds intimidating.
The situation escalates when Natsumi notices Yamato looking in their direction and accuses him of being "creepy." Saki, amused, deliberately shifts her position, inadvertently revealing her underwear to Yamato, which Akari quickly points out, further labeling him a "pervert." Despite Yamato's apologies, Natsumi kicks his chair repeatedly, her short skirt revealing her underwear with each kick. Saki then playfully teases him, and Akari speculates he might be looking at erotic magazines.
Saki then leans in close to Yamato, startling him, and peers at his novel. When she discovers it's a light novel, she, Akari, and Natsumi become intensely curious about his appearance, speculating he might be a hidden "ikemen" (handsome guy) beneath his "in-kyaku" (introverted, nerdy) facade. Saki attempts to remove his glasses and push back his bangs, but Yamato resists. However, Saki playfully blackmails him by reminding him of seeing her underwear, and Yamato reluctantly allows her to remove his glasses and push back his bangs. To their astonishment, Yamato is revealed to be exceptionally handsome, causing the three girls to blush and become flustered.
This revelation triggers a flashback for Yamato, detailing his past. He recalls being popular in elementary school due to his looks and abilities, but this led to uncomfortable situations with girls vying for his attention, and he inadvertently caused one girl to be ostracized. He then explains the societal shift to a polygamous system due to declining birth rates, which allowed his mother's three close friends to become his stepmothers. This led to a large, blended family and a significant change in his life. He adopted a "plain" appearance to avoid the attention he received in elementary school, which he found overwhelming. This decision led to him transferring schools and becoming more reclusive, immersing himself in games and novels.
Back in the present, the three girls, now flustered by Yamato's good looks, invite him to join their group. They suggest calling each other by their first names, and Yamato, still processing the situation, agrees to consider it later. Their conversation is interrupted by the homeroom teacher.
Later, during lunch, Yamato is confronted by three "char-o-dan" (flashy, playboy-type) classmates, Uesugi, Takeda, and Sanada, who try to force their way into eating with the girls. Yamato cleverly evades Uesugi's attempt to take his seat, causing him to fall. Uesugi retaliates by grabbing Yamato's shirt, tearing off buttons. Yamato, wanting to avoid further conflict and the attention it brings, leaves the classroom with his lunch and novel, heading for the rooftop.
He finds the rooftop locked and ends up eating on a landing. He is found by Saki, Akari, and Natsumi, who have brought him lunch and, to his surprise, have found and collected the buttons from his torn shirt. They express their concern and offer to sew them back on. Yamato, touched by their kindness, begins to feel a connection with them, realizing that his previous assumptions about "gyaru" were superficial. They exchange contact information, and Yamato is added to their group chat, which is amusingly named "Yamato's Room."
The next day, Yamato learns that the three char-o-dan have been suspended for theft, including his own bag. He also encounters Tokukawa Saiki, a popular classmate, who makes a condescending remark about Yamato "dating" the three girls. The girls, however, have embraced the rumor as a way to deter unwanted attention from guys like Tokukawa, and they now walk to school with Yamato, forming a protective circle around him. Tokukawa, clearly annoyed, tries to assert dominance, but the girls firmly dismiss him.
Later, during a co-ed gym class, Yamato, still in his plain attire, surprises everyone, including Tokukawa, by displaying exceptional basketball skills, leading his team to victory against Tokukawa's. The girls cheer him on, and a rival girl, Shi Urayama, becomes intrigued by Yamato's hidden abilities and the girls' apparent affection for him.
During lunch, Akari kisses Yamato on the cheek as a "reward" for his basketball performance, followed by Natsumi's attempt to do the same, which is interrupted by Saki. Yamato, though flustered, begins to accept their playful advances. He also learns that the girls have decided to study together for upcoming exams at their apartment.
At the girls' apartment, Yamato is again flustered by their casual display of their bodies, particularly their midriffs. He struggles to maintain his composure and avoid being labeled a "pervert" or "mutturi" (perverted and secretive). He also discovers their shared love for manga, including one he enjoys, "Busou Tensei," which features a protagonist who overcomes hardship through good deeds. The girls express their desire to study with him, and he agrees, despite his initial reservations about their academic performance.
