"Zashiki Onna" is a horror manga series that revolves around a mysterious and unsettling phenomenon involving a supernatural entity known as the Zashiki Onna, or "Tatami Room Woman." The story begins with a series of urban legends spreading among high school students, claiming that a pale, long-haired woman in a white kimono appears in homes, sitting silently in the tatami room. Those who encounter her are said to suffer from inexplicable misfortunes or disappear entirely.

The narrative follows a group of high school students who become entangled with the Zashiki Onna after one of them, a boy named Takuya, hears about the legend and dismisses it as a mere rumor. However, when his friend Yumi claims to have seen the woman in her home, the group begins to investigate the phenomenon. As they dig deeper, they uncover a pattern of disappearances and tragedies linked to the Zashiki Onna, suggesting that the entity is more than just a myth.

The Zashiki Onna herself is depicted as a silent, emotionless figure who appears without warning, often in the corner of a room. Her presence is accompanied by an eerie atmosphere, and her intentions remain ambiguous throughout the story. The students' attempts to understand or confront her lead to escalating tension and a sense of dread, as they realize that the Zashiki Onna cannot be easily escaped or reasoned with.

As the story progresses, the group discovers that the Zashiki Onna is tied to a tragic past involving a woman who was wronged and whose spirit now seeks vengeance. The manga explores themes of guilt, retribution, and the consequences of ignoring or dismissing the supernatural. The characters' interactions with the Zashiki Onna reveal their fears and vulnerabilities, as they struggle to survive her relentless pursuit.

The series is structured around a series of interconnected incidents, each highlighting different aspects of the Zashiki Onna's influence and the growing desperation of the characters. The narrative builds toward a climactic confrontation, where the students must face the truth about the entity and their own roles in the unfolding tragedy. The ending leaves lingering questions about the nature of the Zashiki Onna and the extent of her power, reinforcing the sense of unease that permeates the story.