In a worn-down Tokyo boarding house called Maison Ikkoku, a poor student named Yusaku Godai lives among a group of eccentric and troublesome tenants. The middle-aged, mysterious Yotsuya delights in gossip and voyeurism; the flashy Akemi Roppongi works at a local bar and often parades around in her underwear; and the alcoholic Hanae Ichinose, along with her young son Kentaro, constantly barges into Godai's room for drinking parties. As a ronin, a student who has failed his college entrance exams, Godai finds it impossible to study amidst the chaos and decides to move out. Just as he is about to leave, a beautiful and elegant young woman named Kyoko Otonashi arrives to take over as the new building manager. Godai falls instantly in love with her and immediately changes his mind.

Kyoko is a recent widow, having lost her husband, Soichiro, who was her high school teacher, shortly after their wedding. She carries this deep sadness with her, keeping a large white dog named Soichiro as a living memory. Her in-laws, who own the building, have given her the job as a way to help her move forward. Godai, determined to win her heart, decides to turn his life around and get into a good college. Kyoko, in turn, takes an interest in his success and helps him with his studies, trying to keep the other residents from disturbing him. However, their budding relationship is complicated by the arrival of Shun Mitaka, a handsome, wealthy, and charming tennis coach who also falls for Kyoko. Mitaka is a perfect gentleman on the surface but is secretly terrified of dogs, which Kyoko always has by her side.

The story follows the long, frustrating, and often hilarious journey of Godai and Kyoko as they navigate a series of misunderstandings. Godai is frequently seen with the sweet and innocent Kozue Nanao, a girl he met at a part-time job, leading Kyoko and Mitaka to mistakenly believe she is his girlfriend. Later, while student teaching at Kyoko’s old high school, Godai attracts the unwanted attention of a bold and precocious student named Ibuki Yagami, who aggressively pursues him. Each potential rival only serves to highlight the deep, unspoken feelings Godai and Kyoko have for each other. Through years of struggle, Godai eventually passes his exams, graduates from college, and searches for a stable job, while Kyoko slowly comes to terms with her past and opens her heart to the possibility of loving again.

The setting of Maison Ikkoku itself becomes a central character, a dilapidated but charming old apartment building that acts as a sanctuary for its flawed but lovable residents. Over time, the initially annoying neighbors become a bizarre but supportive family, pushing Godai and Kyoko together through their schemes, parties, and constant interference. The narrative arcs culminate in Godai finally securing a teaching position and proposing to Kyoko. After overcoming her lingering guilt and memories of her first husband, she accepts. The story concludes years later with the married couple returning to Maison Ikkoku with their newborn daughter, Haruka, closing the circle on the place where their love story began.