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)

An unaired 26th episode that will be in the final DVD.

Hida Kizuna possesses the HHG (Heart Hybrid Gear) ability, but it is not strong enough to make him particularly important. His older sister calls him to transfer to a strategic defense school, where many of the students (many of which are large-breasted girls) use their HHG abilities to fight invaders from another world while wearing extremely skimpy pilot outfits. Kizuna's fighting ability doesn't measure up, but his sister has another plan—apparently having erotic experiences with Kizuna will allow the girls to replenish their energy or power-up. It looks like his new school life is going to be full of embarrassment. (Source: MangaHelpers)

Dorogoza Island is rich in "Drop Energy" that players can use on friendly monsters. Once strong enough, they can face enemies in puzzle wars. Winners reap rewards, but what happens to the losers? Only the brave can take on these monstrous challenges! (Source: FUNimation)