Ataru Moroboshi Toshio Furukawa and Lum Fumi Hirano are students at Tomobiki High School, busy with plans for the upcoming student cultural festival. A growing unease sweeps through the group as some begin to suspect that their days are repeating, a theory that only deepens as strange gaps in time and memory slip into their routine. To test the idea, the class is sent home early, and everyone is effectively corralled back to the same place, unable to leave the city limits. This eerie confinement becomes their first clue that something impossibly surreal is happening, and the sense of time looping is soon joined by others’ odd behavior and peculiar occurrences.
Seeking answers, the students eventually board a Harrier jump jet and rise above the familiar streets, only to discover something astonishing: the entire city rides on the back of a gigantic turtle, suspended in the vast emptiness of space. The revelation reframes everything they thought they knew about their world, turning a high school mystery into a cosmic oddity. They press on, returning to the school to investigate its role as the epicenter of the strange happenings, hoping to uncover the cause of the inexplicable events that have begun to feel like a shared nightmare.
As the investigation deepens, seemingly impossible sights unfold around them. Ataru is chased by his own reflections in an infinity mirror, a surreal sequence that underscores how fragile reality has become. The environment shifts before their eyes: once-familiar buildings crumble into ruin, electricity becomes scarce, and only a handful of survivors move through a decaying landscape that resembles a post-apocalyptic setting. Yet not everything is forsaken—Ataru’s parents’ house still functions with electricity and gas, and the local corner store continues to provide food, offering a fragile thread of continuity amid chaos. The group corners a dream demon, coaxing him into revealing his plan: to craft an endless dream that would exist without the nightmare-devouring spirit that haunts dreams. In a bid for power, the dream demon schemes to sever the link between dreams and nightmares, a move that could lock everyone in a loop of perpetual fantasy.
To counter this, Ataru summons the nightmare eater, a creature whose appetite could end the dream’s menace. This act is prompted by a realization that Ataru’s dream world needs a different balance—one in which Lum is not part of his dream “harem.” The consequence is a collapse of the dream’s fragile structure, and Ataru finds himself waking up inside the school, surrounded by his fellow students. The dream’s echoes linger as Lum recounts a fragment of the dream she had, provoking a awkward, tender moment when she asks to kiss him, leaving Ataru flustered and self-conscious in the presence of everyone else.
Unknown to the others, the dream demon and the dream eater continue to be at work behind the scenes, shaping the festival’s momentum and the strange atmosphere that surrounds them. The demon hints at a chilling resolve to “keep up” with Lum and Ataru, suggesting that the threat may outpace their attempts to wake from the dream and restore order to their world. The story lingers on the tension between waking life and the dreamscape, as the festival promises to be both a celebration and a battleground for what is real. In the end, the line between dream and reality remains blurred, leaving the students to navigate a city that feels both familiar and utterly transformed, with the fate of their world hanging in the balance as they face the consequences of the dream demon’s ambitions.
