The story introduces Ichijou Takuya, an ordinary high school freshman who prioritizes his part-time convenience store job over school social circles. He deliberately chose a store away from his school to avoid classmates. His life is disrupted by Saegusa Shion, a beautiful, intelligent, and popular classmate who is secretly the former center of the national idol group "Angel Girls" (known as "Shiolin"). Shion retired from idol activities to attend high school, maintaining a perfect idol persona at school.
Takuya, who views idols as distant figures, is constantly bewildered by Shion's "mystery actions." At his convenience store, Shion frequently appears heavily disguised in a mask, glasses, and cap, exhibiting extremely suspicious behavior like rapid movements, quick purchases, fumbling with money, and even reading magazines upside down. Takuya recognizes her but pretends not to, out of consideration for her apparent attempt at anonymity.
A significant turning point occurs with a class seating change. Takuya, who prefers solitude, is surprised to find his new seat is directly next to Shion's. His childhood friend, Yamamoto Takayuki, a popular and athletic "nice guy," also ends up in front of Takuya, fostering a comfortable dynamic. Shion, however, reacts with flustered embarrassment when Takayuki introduces Takuya, revealing she already knows him.
Their proximity leads to more direct, albeit awkward, interactions. During a pop quiz, Shion, who scores perfectly, leaves a cryptic note ("shion-s.1012") on Takuya's 70-point paper, which Takuya dismisses as another strange act. Later, during lunch, Takayuki introduces Takuya to the popular new girl band DDG and their vocalist YUI. Shion, sitting beside them, reacts with exaggerated physical mishaps (slipping, falling off her chair) whenever Takuya praises YUI, subtly revealing her competitive nature for his attention.
Shion's attempts to connect become more direct. After school, when a classmate invites everyone to karaoke, Shion looks to Takuya for a reaction. Takuya declines due to work, stating he dislikes group karaoke but admits a slight interest in Shion's singing. Shion, visibly disappointed, declines the invitation herself, puffing out her cheeks in a "fugu face." Later, at the convenience store, she directly asks Takuya if he dislikes karaoke. Takuya, maintaining his professional demeanor, replies that he enjoys it, especially listening to good singers, and subtly compliments her singing. Shion blushes and leaves happily.
The narrative builds towards a major discovery when Takayuki invites Takuya to a DDG concert. Shion overhears Takuya's excitement for YUI, reacts with despair, and mutters, "I absolutely cannot lose to YUI-chan," confirming her rivalry for Takuya's interest. While buying DDG merchandise, Takuya encounters an undisguised Shion at an idol goods store. She buys a penlight, signs an Angel Girls T-shirt, and gifts it to a bewildered Takuya, blushing intensely. He later realizes she paid with coins there, contrasting her usual "no coins" habit at his store, highlighting the deliberate nature of her convenience store persona.
At the DDG concert, Takuya is deeply impressed by the live music. The concert takes an unexpected turn when Angel Girls appear as a surprise guest. Takuya is further stunned when Shion, now elegantly dressed and made-up, appears beside him in the audience. Angel Girls' leader, Akari, spots Shion and dramatically calls her onto the stage. After a moment of feigned hesitation and a meaningful look at Takuya ("Listen to my song properly, okay?"), Shion steps onto the stage for a one-day revival as "Shiolin." Takuya is mesmerized by her powerful, angelic voice and perfect idol performance, realizing this is her "true face."
The next day, Takuya, still reeling from the concert, encounters Shion back in her suspicious disguise at the convenience store. He is now flustered by her presence, seeing her in a new light. When Shion notices his concert wristband, Takuya, with an "operating smile," tells her it's from his favorite idol, "Angel Girls' Shiolin." Shion blushes intensely and rushes out, but Takuya catches her happy expression. His perception of Shion has transformed from a distant idol and suspicious classmate to a multi-faceted individual whose talent he now deeply admires, while also finding her disguised persona endearing.
