"Yakimochi Caprice" centers on the romantic and comedic misadventures of its main characters, exploring themes of jealousy, unrequited love, and personal growth. The protagonist, a high school student named Haru, harbors feelings for his childhood friend, Yuki, who is oblivious to his affections. Yuki, cheerful and outgoing, often unintentionally fuels Haru's jealousy by interacting closely with other boys, particularly the popular and charismatic Riku. This dynamic creates a series of humorous and heartfelt situations as Haru struggles to balance his emotions and express his true feelings.

The narrative unfolds through episodic encounters, each highlighting Haru's internal conflict and his attempts to navigate his jealousy, often referred to as "yakimochi" in Japanese. His overactive imagination frequently leads to exaggerated scenarios, adding a layer of slapstick comedy to the story. Meanwhile, Yuki remains largely unaware of Haru's turmoil, treating him with the same casual affection she has shown since childhood. Riku, though initially portrayed as a rival, gradually reveals a more nuanced personality, complicating Haru's perceptions and adding depth to their interactions.

Supporting characters, such as Haru's sharp-tongued friend Aoi and Yuki's protective older sister Sora, contribute to the series' comedic and emotional beats. Aoi often serves as a voice of reason, calling out Haru's irrational behavior, while Sora provides a protective yet teasing presence, adding tension and humor to the group dynamic. The series balances lighthearted moments with subtle explorations of insecurity and self-doubt, particularly through Haru's journey toward understanding his emotions and finding the courage to be honest with himself and others.

The plot progresses through a mix of school life scenarios, casual outings, and unexpected events that test the characters' relationships. While the central focus remains on Haru's unspoken feelings for Yuki, the series also touches on themes of friendship, self-acceptance, and the complexities of young love. The episodic structure allows for a variety of comedic and emotional tones, ensuring a dynamic and engaging narrative. By the end, "Yakimochi Caprice" delivers a satisfying blend of humor and heartfelt moments, capturing the awkward yet endearing nature of adolescent romance.