Tenma Tsukamoto is a bubbly, clumsy high school sophomore deeply in love with Karasuma, an eccentric, stoic classmate who responds to her elaborate love letters with baffling non-sequiturs, like announcing his intention to morph into a giant sea slug. Desperate to win his affection, Tenma relies on wild, overly complicated schemes cooked up with her eclectic friends, completely oblivious to the fact that her terrifying classmate, Kenji Harima, is harboring an intense, secret crush on her. Harima, a reformed juvenile delinquent, turns to manga creation after a fateful
misunderstanding with Tenma, pouring his unrequited anguish into his artwork while constantly agonizing over how to confess his true feelings.As the series progresses, the romantic web expands into a chaotic love triangle and massive ensemble
comedy of errors. Tenma’s aloof younger sister, Yakumo, possesses a secret ability to hear the innermost thoughts of anyone who harbors feelings for her, quickly discovering Harima’s deep devotion to her sister and often acting as his unwitting confidante. Meanwhile, the school's social hierarchy is upended by the aristocratic and competitive Eri Sawachika, who develops a complicated, bickering rivalry with Harima after being accidentally entangled in his delinquent past. Friendships are tested and forged during class trips, sports festivals, and grueling exam-study sessions, where characters continuously misinterpret each other’s romantic intentions.Drama escalates when Harima experiences a profound creative crisis, abruptly vanishing to live as a hermit in the wilderness, where he reconnects with nature and refines his artistic passion. During his absence, the remaining students grapple with their own shifting emotions. Eri struggles with her growing, undeniable affection for the runaway delinquent, while Tenma continues her hopelessly dense pursuit of Karasuma, entirely unaware of the profound personal sacrifices Harima made for her happiness. Upon his dramatic return with a completed masterpiece manga, Harima finds himself at a moral crossroads regarding his career and his love life.The narrative reaches a bittersweet crescendo when Karasuma is struck by a sudden, mysterious memory-loss illness that forces him to withdraw from school. In a final, desperate bid to grant Tenma her heart's desire, Harima channels all his remaining emotional strength into carrying Tenma on a bicycle across the countryside so she can reach Karasuma one last time. Ultimately, the series concludes with poignant ambiguity: Karasuma departs for America to undergo experimental medical treatment without giving Tenma a definitive romantic answer, while Harima continues his daily routine, forever trapped in the beautifully agonizing cycle of unrequited love, teenage longing, and creative resilience.