Bundled with the fifth manga volume.

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. (Source: MU, edited)

Despite the Ends’ attack on Verlina being successfully repelled, the war has not yet ended. With the monster armies regrouping, the Black King tightens his grasp on the already conquered territory. New conflicts erupt all across Orte, as its remaining forces struggle to retain control over long-oppressed demi-human races. While Ends grow more potent each day, Toyohisa Shimazu remains unconscious after heavy injuries suffered during the Battle of Verlina. Facing enemies on every side, humanity’s fate is still on a knife's edge.

Twenty years prior to the story's beginning, an asteroid headed for Earth destroys Pluto. Due to Pluto's destruction, the asteroid, which is dubbed Thanatos, becomes temporarily stagnant. Now, in order to avoid Earth's impending destruction, the International Solarsystem Development Agency (ISDA) works on the D-Project, and creates the Dragonaut after finding a dragon egg under the ocean. This weapon's primary purpose is to destroy the asteroid when the time comes. However, they soon find out that the asteroid is not their only threat, as powerful dragon-like creatures, which are bent on destruction, appear on Earth. After witnessing a murder by one of the creatures, Jin Kamishina, a lonely 18-year-old boy who lost his family in a shuttle accident two years ago, gets involved in the mysteries of the dragons and becomes the chosen pilot of the Dragonaut. Helping him on his journey is Toa, a mysterious girl who saves him from falling to his death after the creature attacks him. As they get deeper into the mysteries of the dragons, they encounter new friends and enemies, and also begin to develop a closer relationship. (Source: Wikipedia)