The story follows the adventures of Ethan Kendrick, charged in his childhood by Jack to protect the Yeouiju, an individual born able to change an Imugi into a Celestial Dragon. To this end, Jack gives Ethan a medallion formerly belonging to Haram and reveals that the Yeouiju is Sarah, whom Ethan will find in Los Angeles.
15 years after this revelation, a corrupt Imugi identified as "Buraki" invades the city, bent on capturing Sarah; whereupon Ethan, now a televised-news anchor, rescues her, conveys the knowledge of her purpose, and attempts to save her from Buraki. During the resulting chase, Buraki's "Artox Army" enters the city and engages the United States Army, the United States Air Force, and the Los Angeles Police Department in battle. Here, the Atrox Army is shown to consist of black-armored, humanoid warriors; theropod-like cavalry called "Shaconnes"; small, winged Western dragons called "Bulcos"; and immense, slow-moving reptiles carrying rocket-launchers on their backs, identified in the dialogue as "Dawdlers". Despite losses, this army overwhelms the human forces, while Ethan and Sarah escape. They are subsequently captured by the Bulcos and taken to a menacing fortress in the midst of a darkened desert landscape. There, Ethan's medallion destroys the Artox Army; but Buraki attempts to consume Sarah, whereupon he is attacked by the Good Imugi. The two Imugi, good and evil, engage each other in a duel that Buraki appears to win after seemingly snapping the Good Imugi's neck. Having won the fight, Buraki again approaches Sarah; but having offered herself to him, she instead gives her power to the Good Imugi who had just revived, who thereupon becomes the Celestial Dragon, continuing the duel until it finally destroys Buraki.
After Buraki is destroyed, Sarah dissolves into a spirit form, and the Celestial Dragon permits Sarah to speak to Ethan, whom she promises to "love...for all eternity"; then withdraws Sarah into his body and ascends to the heavens. Immediately Jack appears behind Ethan, reminds him that the two of them "have been given a great honor" to take part in this transformation, and vanishes; presumably never to be seen again. After whispering "Goodbye old man", Ethan walks away into the desert.