The narrative unfolds primarily at Maison Ikkoku (一刻館, Ikkoku-kan), a dilapidated boarding house located in the fictional district of Tokeizaka (時計坂; "Clock Hill") in Tokyo, where college hopeful Yusaku Godai resides. Godai is a kind-hearted, albeit indecisive individual who often finds himself being taken advantage of by the eccentric residents of Maison Ikkoku, which include a voyeur named Yotsuya, the audacious Akemi Roppongi, and the Ichinose family, notably the gossiping and frequently inebriated stay-at-home mother, Hanae Ichinose.
As he is on the verge of moving out, a beautiful woman named Kyoko Otonashi (née Chigusa) suddenly appears to inform him that she will be taking over as the boarding house's manager. Instantly captivated by her, Godai decides to remain at Maison Ikkoku. It soon becomes apparent to Godai and the other tenants that despite her youth, Kyoko is a widow; her husband, Soichiro, a high school teacher, died shortly after their marriage. Filled with compassion for Kyoko's sorrow, Godai is determined to help her find happiness again.
As his feelings intensify, Godai works up the courage to express his love for Kyoko. However, just as their budding romance begins to take shape, she meets the charming and wealthy tennis coach Shun Mitaka at her local tennis club. Mitaka expresses his desire to pursue Kyoko and asserts that he is willing to wait until she is ready to love again. Godai, unwilling to concede, continues to pursue Kyoko, but a misunderstanding arises when Kyoko sees him with the innocent Kozue Nanao, who he previously met during one of his many part-time jobs. This encounter leads Kyoko to mistakenly believe that Kozue is Godai's girlfriend, a perception that Kozue herself shares.
Feeling betrayed, Kyoko starts dating Mitaka openly. Despite these complications, the affection shared between Kyoko and Godai becomes increasingly evident as they navigate misunderstandings and trials throughout the series. Eventually, Godai successfully gets into college and, with support from the Otonashi family, he takes on a student-teaching position at Kyoko’s former high school. Here, he captures the attention of a bold student named Ibuki Yagami, who begins to chase after him, bringing a contrast to Kyoko’s more reserved character and prompting her to confront her own feelings for Godai.
Meanwhile, Mitaka struggles with a fear of dogs, which presents an obstacle since Kyoko owns a large white dog named Soichiro, in memory of her late husband. Mitaka eventually confronts his phobia, but when he is ready to propose to Kyoko, family pressures push him towards an arranged marriage with the pure and innocent heiress Asuna Kujo. As Mitaka becomes more aggressive in courting Kyoko, he comes to realize that Kyoko has chosen Godai and is merely waiting for him to stabilize his life before taking the next step.
Everything shifts when one fateful night, Mitaka, in a drunken stupor, misremembers having spent a romantic night with Asuna. Asuna's subsequent pregnancy announcement forces him to marry her; however, an unexpected twist reveals that it was her dog who is with pups, not Asuna herself. Despite this mix-up, Mitaka acknowledges that he has always valued Kyoko above all else.
As Godai’s circumstances improve, Kozue re-enters his life, announcing her intentions to marry another man. Misunderstandings abound when Godai mentions his own plan to propose, leading both Kyoko and Kozue to misinterpret the situation. Heartbroken and feeling betrayed, Kyoko slaps Godai and insists he leave. When Godai stands his ground, the following morning, he finds that Kyoko has moved back in with her parents, leaving him devastated.
In his attempts to reach out, Godai visits Kyoko daily, but she shuts him out completely. When her anger subsides, Kyoko returns to Maison Ikkoku, where the inhabitants attempt to persuade her to reconcile with Godai. The flamboyant Akemi threatens to seduce Godai if Kyoko continues to hesitate, but it becomes evident that this ploy backfires when Kozue mistakenly sees Godai leaving a love hotel with Akemi, leading her to accept another man's proposal.
Just as Kyoko is about to return, she discovers the situation involving the hotel. Misunderstanding that Godai has betrayed her once again, she lashes out in anger. In a heartfelt moment, Godai chases after her, pleading that she has never considered his feelings amid the chaos of their relationships. He fervently declares his undying love for her, stating that from the first time he saw Kyoko, she has been the only woman for him. This confessional moment finally breaks down Kyoko's walls, allowing her to embrace her feelings for Godai.
As their love blossoms, they consummate their relationship; the next morning, Kyoko reveals her long-held affection for Godai. With the last barriers removed following Godai's successful job acquisition, he proposes to Kyoko. With the approval of both families, they marry and begin a new chapter in their lives together. The story concludes as Godai and Kyoko arrive home with their newborn daughter, Haruka, sharing the tale of how their journey started in Maison Ikkoku, a place that will forever hold special memories for their family.
