"Tomo-chan Is a Girl!" is a romantic comedy anime centered around Tomo Aizawa, a tomboyish high school girl who has been close friends with Junichirou Kubota since childhood. Despite her feminine name and appearance, Tomo is often mistaken for a boy due to her athletic build, assertive personality, and love for martial arts. Jun, on the other hand, is laid-back and perceptive but treats Tomo more like a buddy than a potential romantic interest. This dynamic frustrates Tomo, who has harbored feelings for Jun for years but struggles to convey her emotions in a way that makes him see her as a girl.

The series explores Tomo’s efforts to navigate her feelings while dealing with the challenges of her tomboy identity. Misumi, Tomo’s best friend, provides support and often acts as a mediator, offering advice and encouragement. Carol, another friend, adds a playful and eccentric element to the group, frequently teasing Tomo and Jun about their relationship. The story progresses through a series of comedic and heartfelt moments as Tomo tries to balance her tough exterior with her desire to express her femininity and win Jun’s affection.

Jun’s obliviousness to Tomo’s feelings creates much of the tension and humor in the series. Despite his apparent indifference, subtle moments reveal that Jun does care deeply for Tomo, though he struggles to reconcile his perception of her as a friend with the possibility of a romantic relationship. The interactions between the characters are driven by misunderstandings, playful banter, and genuine emotional growth, making the series a blend of lighthearted comedy and tender moments.

The narrative also delves into the perspectives of the supporting characters, such as Misumi’s own romantic struggles and Carol’s unconventional approach to relationships. These subplots enrich the main storyline, providing additional layers to the dynamics within the group. Through its exploration of friendship, identity, and unspoken emotions, "Tomo-chan Is a Girl!" presents a relatable and engaging portrayal of young love and self-discovery.