"Junji Ito's Dissolving Classroom" is a horror manga series that explores themes of guilt, obsession, and supernatural phenomena through interconnected stories. The narrative centers on the Azawa siblings, Yuuma and Chizumi, whose presence brings about bizarre and terrifying events. Yuuma, a seemingly polite and apologetic young man, harbors a dark secret: his excessive apologies trigger grotesque transformations in those around him, causing their heads to dissolve into a gelatinous substance. His sister, Chizumi, is equally unsettling, with a fanatical devotion to Satan and a penchant for manipulating others into gruesome fates.

The series unfolds in episodic chapters, each delving into the siblings' interactions with various individuals and the chaos that ensues. In one story, Yuuma's apologies lead to the dissolution of a teacher's head during a school visit, while in another, Chizumi's obsession with Satan results in a ritualistic massacre. The siblings' actions often leave a trail of destruction, with their victims experiencing physical and psychological torment. Despite their malevolent nature, the Azawas maintain an eerie charm, drawing people into their orbit before revealing their true intentions.

As the series progresses, the origins of the siblings' powers and their connection to Satan are gradually revealed. Their backstory involves a tragic family history, with their parents' involvement in occult practices and a mysterious curse that binds them to their dark abilities. The narrative culminates in a climactic confrontation, where the full extent of their powers and the consequences of their actions are laid bare. The series blends psychological horror with body horror, creating a chilling atmosphere that lingers long after the final page.