Three hundred years ago, the god of thunder, Taishakuten, rebelled against the Heavenly Emperor, killing both him and the guardian god Ashura-ō. With the help of Ashura-ō's wife Shashi, he usurped the throne and began his cruel reign as the new Emperor. However, a prophecy was made by the stargazer Kuyō, first to Ashura-ō and then to Yasha-ō:
"Six stars will fall to this plane. The dark stars that will defy the Heavens. And you shall undertake a journey. One that begins when you find the child of a vanished race. I cannot discern the child's alignment. I only know that it is he alone who can turn the wheels of Tenkai's destiny. For it is by Heavenly Mandate that through this child, the Six Stars shall begin to gather. And then someone shall appear from the shadows. Even my powers cannot clearly make out his figure, but he knows the future and can manipulate both evil and heavenly stars. A roaring flame shall raze the wicked. Six stars will overpower all others. And inevitably, they will be the schism that splits the Heavens."
Following this prophecy, the Guardian Warrior of the northland, Yasha-ō, awakens the genderless child of Ashura-ō, Ashura, who has slept the last three hundred years under a magical seal. Believing the prophecy to mean that the "Six Stars" together can overthrow Taishakuten, he and Ashura set out to find the "Six Stars". Over time, five of the Six Stars gather as Yasha-ō and Ashura, the first two stars, are joined by Sōma, Ryu-ō and Karura-ō, the other three. A mysterious character who appears and disappears quite regularly, Kujaku, gives them helpful advice, but his nature and intentions are unclear.
The gentle and childlike Ashura (who is usually referred to as "he" out of convenience, though some translations use a female pronoun) soon reveals a deadly alter-ego, a youth who delights in death and destruction, but this side remains for the longest time more or less suppressed, also by Ashura's affection for Yasha-ō.
Seeking to bring Taishakuten's reign to an end, the Six Stars finally enter Zenmi-jō, Taishakuten's palace. They are met there by the three remaining "Four Generals" (Shitennō) (one was killed by Yasha-ō earlier), warriors who swore to protect Taishakuten. The Six Stars are shocked to discover that the sixth Star, Kendappa-ō, their friend and ally, is among them as Jikokuten, the previously unknown general. By the meeting of all the Six Stars, Ashura's dark nature is brought to the surface. He kills his mother, the traitorous Shashi, takes the seal on her forehead and merges it with his sword Shura-tō, to awaken the true Ashura; the god of flame, blood and war, whose aim is to destroy heaven, earth, and hell.
The true Ashura proceeds to complete his awakening by killing the remaining Six Stars (some of them were killed earlier). He kills the stars one by one, absorbing their power, until only Yasha-ō is left. Surprisingly, Taishakuten stands against him. It turns out that his cruel reign was really a plot by him and the deceased Ashura-ō to prevent the gathering of the Six Stars and the true Ashura's awakening. However, it is not Taishakuten who stops Ashura, but Ashura himself. As he is about to give Yasha-ō the finishing blow, Ashura in the last moment stabs himself instead. He is then enveloped in a cocoon and enters into a deep sleep. Ashura is awakened hundreds of years later when Kujaku sacrifices his own life, on Yasha-ō's promise that he will not let Ashura become the God of Destruction again.