Ayumu Fujino, portrayed by Yumi Kawai, is a spirited elementary school student who possesses a natural talent for drawing manga. She spends her days publishing yonkoma (four-panel comics) in her school's newspaper, where she deeply enjoys the praise and admiration she receives from both her classmates and her teachers. However, her confidence is shaken when her teacher requests that she share one of her comic strips with Kyomoto, played by Mizuki Yoshida. Kyomoto is a shut-in struggling with severe social anxiety who harbors a secret longing to draw manga herself.
While Fujino initially agrees to the request with some reluctance, she is soon hit with a shocking discovery: Kyomoto is an exceptionally skilled background illustrator. Kyomoto's ability to create intricate, professional-grade scenic artwork far surpasses Fujino's own technical skills. Consumed by an intense feeling of envy and a desperate need to be the best, Fujino becomes obsessed with surpassing Kyomoto. This drive leads her to isolate herself, alienating her family and friends as she pours every waking moment into improving her art. Despite a full year of rigorous effort and visible improvement, Fujino finds that she still cannot meet Kyomoto's high standards. Ultimately, feeling defeated, she gives up on drawing entirely and attempts to rekindle her social life.
Years later, as her class prepares to graduate from middle school, Fujino is given the task of delivering Kyomoto's diploma to her home. Upon entering the house, Fujino discovers stacks of sketchbooks. In a moment of impulsivity, she draws a mocking yonkoma aimed at Kyomoto, but the paper accidentally slips under the door of Kyomoto's room. Though Fujino tries to flee in remorse, Kyomoto emerges from her room. Instead of anger, Kyomoto reveals that she is actually a massive fan of Fujino, having closely followed her work in the school paper all along. Flattered by this sudden idolization, Fujino lies and claims she stopped drawing only because she intends to enter professional contests. This interaction reignites Fujino's creative spark, and she decides to pick up her pen once again.
Throughout high school, the two form a bond, and Fujino invites Kyomoto to collaborate with her. Their joint effort results in a winning contest entry. The two become close friends, and Fujino uses a portion of their prize money to take Kyomoto on a trip around town. They continue creating manga under the collective pen name "Kyo Fujino", earning high praise for their one-shots. Kyomoto expresses deep gratitude to Fujino for providing the motivation she needed to finally step out of her shell. Following graduation, they are offered a serialization deal with Weekly Shōnen Jump, but Kyomoto chooses to decline the offer to pursue a formal art education at the Tohoku University of Art and Design.
Fujino is deeply upset by this decision but continues her career alone, publishing a manga titled Shark Kick under the name Kyo Fujino. While the series becomes a massive success—spanning eleven volumes and receiving an anime adaptation—the adult Fujino feels a void in her life. She feels unfulfilled without Kyomoto's presence, leading her to struggle with a rotating door of assistants.
Tragedy strikes on January 10, 2016, when a man claiming that Tohoku University plagiarized his work carries out a mass murder with a pickaxe. Kyomoto is among the victims. Devastated by the loss, Fujino places Shark Kick on hiatus and returns to her hometown for the funeral. While alone in Kyomoto's house, Fujino is consumed by guilt, convincing herself that she indirectly caused Kyomoto's death by encouraging her to pursue art. In a fit of despair, she tears up the mocking comic she drew years prior. A small scrap of that paper slips under Kyomoto's door and seemingly travels through time to the day the two first met.
In this altered reality, the scrap of paper alarms Kyomoto, preventing her from leaving her room to meet Fujino. Despite this, Kyomoto still pursues her passion for art and attends Tohoku. However, when the killer arrives, this version of Fujino—who pursued athletics instead of art—physically fights and incapacitates the attacker before he can harm Kyomoto. As Fujino is taken away in an ambulance, the two meet for the first time in a manner similar to their original encounter. Back in the original timeline, a gust of wind blows a drawing—titled "Look Back"—from the alternate reality into Fujino's view. The drawing depicts Fujino saving Kyomoto, drawn in Fujino's childhood style.
Shocked, Fujino enters Kyomoto's room and finds a collection of Shark Kick volumes and merchandise, discovering that Kyomoto had spent her life supporting her and voting for her in reader surveys. Overwhelmed by grief and questioning her life choices, Fujino laments that she hates drawing. It is then that she hears Kyomoto's voice asking:
> "Then, why do you draw, Fujino?"
This question triggers a flood of memories of all the joy her art brought to Kyomoto. Finally coming to terms with the tragedy, Fujino decides to return to her work and continue drawing manga, taping Kyomoto's yonkoma above her workstation as a permanent source of inspiration.
