Seventeen-year-old Kori Momose is searching for an apartment after changing high schools. She finds a seemingly perfect newly built unit with an incredibly low rent, but there is a catch: the apartment is haunted by Muu, the earthbound spirit of a Shiba Inu dog. Kori is unfazed by ghosts but has a deep fear of dogs, stemming from a recent incident that forced her to transfer schools.

The setting is the Maison Shiba, an apartment building constructed on the site of a former unethical puppy mill. The ghosts residing there are jibakurei, spirits of dogs who died tragically and remain tied to the location because they never experienced love or kindness during their lives. Kori learns from a neighbor that showing genuine affection to these spirits allows them to ascend to heaven. Believing this will be an easy way to get her apartment to herself, she decides to move in.

The main characters are Kori, a solitary and emotionally reserved girl who struggles to fit in with others, and Muu (also called Mu-chan), a particularly grumpy and distrustful Shiba Inu ghost with a permanent scowl. Their cohabitation begins chaotically, marked by Muu’s biting and Kori’s initial plan to quickly shower him with affection so he will disappear. However, she discovers this is not so simple, as Muu resents humans due to the abuse he suffered.

As the story progresses, the pair begin to understand each other's painful pasts. Kori learns about the tragic history of the puppy mill, while Muu gradually starts to warm up to her, revealing a softer side. The narrative focuses on their slow, halting friendship, which helps heal both characters. Kori abandons her goal of exiling Muu and instead decides to give him a happy life for however long he remains on Earth. The manga blends comedy, derived from Muu's expressive faces and the eccentric human residents, with supernatural slice-of-life elements and emotional moments about loss, trust, and overcoming isolation.