Two martial artists are brutally killed by a team of assassins, leaving their wards, a young boy and girl, defenseless. A martial arts master dispatches of the assassins, sparing their lives, and decides to take them in. He raises them and teaches them martial arts.

A long time ago, there was a valiant swordsman who came to be known simply as "the hero." There was a demon who has caused people suffering. The hero and his companions arrived to challenge the demon to a battle and by combining their powers, the battle was brought swift conclusion. With no one around to cause trouble, the island became a quiet place where everyone could live together in peace. Several years later, the demon is revived. Our present-day protagonist, Dai, lives on a remote island in the southern seas and dreams of becoming a great hero. When he hears about the demon's revival, Dai and his friends take it upon themselves to stop him and the evil force that revived him. Along the way, Dai discovers the identity of "the hero," the truth behind the evil force who revived the demon, and Dai's own hidden powers that surface in times of peril.

Winter is approaching, and Myne—now an apprentice priestess—must prepare for her stay at the church and the upcoming Dedication Ceremony. However, due to her immense knowledge and extraordinary amount of mana, she has garnered the attention of many dangerous people, who are willing to do anything to get their hands on Myne. To keep her safe, the Head Priest assigns Myne a bodyguard and advises her to be adopted by a noble, a decision that will force her to leave her family behind. As Myne is opposed to the idea, the Head Priest gives her an ultimatum: she can be with her family until she turns 10, but if she is deemed too unstable, she will immediately be dealt with. Placed in a tough position, Myne is uncertain about her future. Despite the twists that may lie ahead, she will do whatever she can to protect those that she loves—even if it means giving up on her dream.

In this prequel to the "X" TV series, a beautiful, young, bedridden dreamgazer named Kakyou remembers the life and death of a remarkable young woman whom he met in dreams. He also recounts his dreams of a tragic future in which the fate of the Earth will be decided.