Hiruko the Goblin

Hieda, a young archaeologist, is discredited for wild theories. A letter from his brother-in-law Takashi Yabe reveals the discovery of an ancient tomb built to seal a yokai. Yabe and his student Reiko Tsukishima investigated the burial mound but vanished under mysterious circumstances.

Hieda travels to the town to investigate the matter and meets Masao, Yabe's son. Masao had searched the school for his father and seen Reiko at the schoolhouse, seemingly seducing his classmate Kono. He is plagued by strange afflictions: his back heats up, smoke rises, and small, blackened faces of the dead appear on his skin.

Masao and Hieda search the schoolhouse and discover that Kono, along with his friends Aoi and Katagiri, have been brutally murdered with a switchblade. The grisly scene leads them to suspect the janitor Watanabe, who had been trying to keep people away from the schoolhouse.

Ultimately they discover that the culprit is the disembodied singing head of Reiko. The janitor Watanabe, who had tried to keep people away from the schoolhouse, is initially suspected because of his behavior surrounding the site.

While investigating, Hieda finds Yabe's notebook confirming that the tomb seals Hiruko, a yokai. Believing Hiruko is behind the incidents, Hieda resolves to learn the spells to open and close the burial mound sanctum. This prompts the team to seek the means to access the sealed chamber.

Watanabe cuts the power lines to the schoolhouse and attacks Hieda and Masao. Masao manages to wrest the gun away from him. The confrontation heightens the danger surrounding their investigation.

Back at the schoolhouse, Reiko appears with spider-legs. Watanabe attacks Hieda while Reiko targets Masao. The escalating threats force the pair to press on despite the danger.

The group escapes from the schoolhouse, but Reiko grows insect-like wings and the chase resumes. A later confrontation is interrupted when bug spray repels her, allowing them to pull away.

Watanabe explains that as a child he knew Tatsuhiko Yabe, Masao's grandfather. Tatsuhiko bore scars of dead men's heads on his back and had somehow sealed the gate 60 years ago. He swore to guard the schoolhouse after his death to prevent a recurrence.

The group realizes Masao's father had reached the interior of the chamber, but was betrayed. The Yabe family crown (the seal) is missing and likely taken by Takashi. It remains inside the sealed chamber.

Having been corrupted by Reiko, Watanabe realizes she is corrupting him. He turns the gun on himself and dies, ending his struggle.

At the burial mound, Hieda uses a Kojiki-based spell to open the sealed chamber, invoking the tale of Izanagi and Izanami. Inside they find Hiruko, the helmet crown, and Masao's father, who has become a spider-legged abomination.

As they flee, Reiko and her transformed victims block the exit, but the victims unexpectedly allow passage and help them reach the tomb entrance. Hieda then recites the incantation to close the gate.

Believing the danger is over, Reiko secretly clings to Hieda's back and uses memories of his dead wife to press him into reopening the gate. This moment tests their resolve as the threat resurges.

Masao discovers the helmet's horn count—three horns—and performs the closing incantation once more. Hiruko-possessed Reiko is finally driven back into the underworld.