In a remote village in the province of Tanba, a household of peasants cowers during a series of earth tremors that are interpreted as the escape attempts of Arakatsuma, also known as Daimajin, a violent divine spirit said to be trapped within the nearby mountain held in fear and reverence by the locals. As the village gathers at the localshrine to perform an ancient ritual to pacify Daimajin, Ōdate Samanosuke, chamberlain to the local lord Hanabusa Tadakiyo, stages a coup d'état. He and his henchmen slaughter Hanabusa and his wife, but their son and daughter escape, aided by the heroic samurai Kogenta. Back at the shrine, Samanosuke's men break up the ceremony, forbidding all such gatherings in the future. The elderlypriestess, Shinobu, issues a dire warning, but the men ignore her. Kogenta takes the two children to his aunt Shinobu's house. The priestess takes them up the mountain, into forbidden territory, where a gigantic stone idol of the mountain god who had sealed Daimajin long ago stands half-buried atop a waterfall. Near this idol is an ancient temple - safe as only Shinobu knows of its existence. The children grow to adulthood. The son, Tadafumi reaches his 18th birthday. The years have been miserable on the villagers. Samanosuke is a brutal leader who is using every man in the starving village as slave labor. The place is ripe for revolution, and surviving Hanabusa retainers are starting to return. Kogenta journeys to the village to try to gather the old retainers, but gets himself captured. A boy, Take-bō, gets word to Tadafumi and his sister, Kozasa that their friend is a prisoner. Tadafumi tries to rescue him, only to discover it's a trap. With both awaiting execution, Shinobu tries to talk to the tyrant, warning him that the god of the mountain's curse will befall him should he continue his evildoing ways. Samanosuke, refusing to heed Shinobu's words, kills her and orders the idol demolished. With her dying breath, Shinobu curses Samanosuke to die a harsh, merciless death and declares that if he attempts to destroy the idol, the wrathful Arakatsuma sealed inside it will come out. The crew that travels up the mountain to smash the idol accidentally discovers Kozasa and Take-bō, and force them to take them to the statue. The soldiers bring out an enormous chisel and proceed to hammer it into the idol's head; they stop when they see blood beginning to drip from it. Horrified, the men attempt to flee, but the earth cracks open and swallows them. Kozasa begs the god of the mountain to save her brother and Kogenta and punish the wicked Samanosuke. At the fortress, Tadafumi and Kogenta are tied to large crosses, awaiting their fates. Kozasa offers her life to the god and attempts to throw herself over the nearby waterfall, but the rock and earth covering the lower half of the idol fall away, and it comes to life. As it walks out into the clearing, Kozasa prostrates herself before it; the idol, animated by the reawakened Daimajin Arakatsuma, assumes a terrifying appearance and goes to Samanosuke's stronghold. Daimajin rescues both Kogenta and Tadafumi and proceeds to utterly destroy the fortress. After impaling Samanosuke with the chisel on its forehead, Daimajin now turns its wrath upon everyone in sight. Take-bō unsuccessfully begs Daimajin to stop; as the boy was about to get trampled on by the idol, Kozasa steps in and saves him. Kozasa tearfully pleads Daimajin to cease its rampage, letting her tears fall on its stone feet. Its anger now quelled, Daimajin's spirit leaves the idol, restoring it to its former appearance before it collapses into a heap of rubble.
Daimajin was released theatrically in Japan on April 17, 1966. The film was released simultaneously in the United States with English subtitles by Daiei International Films and in an English-language dub by Bernard Lewis.
