There is a realm which lives in constant fear of an evil dragon that lives on its outskirts. The dragon is not only evil, but also pretty much all-powerful, so you don't want to cross it...ever. Because of the dragon's influence over the realm, the kingdom's main religion is "dragonism", also known as the Draconic faith. In general, though, the dragon leaves the kingdom in peace, with one small exception. He demands that a young girl be brought to his cave, for him to keep as his prisoner. That girl is forced to sing and dance for him, until she starves to death or collapses from exhaustion. A new "Dragon Diva" is selected whenever one dies. This is pretty much the only thing the dragon demands of the kingdom, so in general, the country's people are more than happy to get the heck out of his way when he's choosing his next victim, or even openly help him, if it means that he'll refrain from wreaking any other kind of havoc on their realm. This is the story of Rin, the current Dragon Diva, and her twin brother Len's quest to save her from the dragon's evil clutches.
Part 1- Kimiwo Sagasu Sora (Searching the Skies for You)
The video opens, and we see Miku, dressed as some sort of masked priestess. She guards the dragon's cave, so that no one may interfere with this plan to protect the kingdom. She was actually a dragon herself once, an exceptionally powerful and magical one who had the ability to periodically take on a human form. Long ago, she was enslaved by the priests of dragonism, who put a mask on her that not only forced her to stay in human form, but also blurred her memory of being a dragon and allowed them to control her. She has a flashback about past Divas, including one played by Teto, who was the last Dragon Diva before Rin.
The picture fades to show a young blond woman, happy with her twin son and daughter. Some soldiers come to the door with a Royal Decree, and take the baby girl away, so that she will grow up to dance for the dragon.
Present time. Rin stands in the cave, holding her treble clef necklace. She hears the dragon, and it drops to the floor. We see Len picking it up (symbollically, most likely. I mean, why would he need to look for her if she was standing right there?), and looking up to the sky. He begins his quest to find Rin. Though Rin and Len were separated as babies and have therefore never actually met each other, it's important to note that, because of mysterious powers of twin telepathy, they are not only aware of each other's existence, but also receive periodic visions and impressions of each other's appearance, voice, and personality. This is why Len is able to fight so desperately for a sister he has never met, and why Rin can hope with such confidence that her brother will come and save her. They may never have met, but this is not to say that they don't know each other.
The video ends with a montage of the people he'll meet on his journey, including Meiko, Gakupo, Luka and Kaito (with Neru and Haku in the background)
Part 2- Hikari to Kage Rakuen (Paradise of Light and Shadow)
The video opens with Rin, singing and dancing for the dragon. It then shows us some other girls who were imprisoned by the dragon, and it focuses on Teto, the most recent Dragon Diva. Then we see Gakupo, being humiliated by Luka who is not only a noble, but also a priestess (sometimes called an "Oracle" or "Prophetess") of dragonism. Fundamentally, this means that she will stop at nothing to make sure that the Dragon Diva system continues undisturbed. Despite her devotion, Luka actually knows less about the dragon and the system surrounding him than Gakupo does. Gakupo is a scholar and dragonism expert serving at Luka's court. Long ago, when Gakupo was a child, his grandfather was the kingdom's leading expert on dragonism, and the only living person to know all of the dragon's secrets. After his grandfather's death, Gakupo and his mother were invited to come live at court, since it was known that the old scholar had been grooming his grandson to be his successor. Most details from Gakupo's backstory flashback sequence in the second video are still unexplained, but what is known is that, at some point, his mother, for unknown reasons, committed suicide by throwing herself off the palace roof.
Gakupo's status as a dragonism expert probably explains his involvement in Luka's plans, given the latter's apparent obsession with the faith. After he decides that he will no longer help her, is arrested, and is subsequently rescued and brought into Len's party, Gakupo puts his knowledge of the dragon to good use as he aids Len in his quest to break the Draconic cycle.
Len comes, and attacks Luka for letting the dragon enslave his sister. Meiko, hired by Luka for protection, defends her, and fights with Len. The reason that Meiko agreed to help Luka is because Luka has told her that as long as the cycle of the dragon's kidnappings is allowed to continue, there is still a chance to bring back the girls who have been lost to him in the past. But if Len succeeds in rescuing Rin, the cycle will be broken, and all hope of saving those past girls will be lost. This is important to Meiko because Meiko's best friend, as we find out, was once taken by the dragon. She is the girl played by Teto that we saw earlier. Meiko was the daughter of a noble, while Teto was a commoner, and, in the time before their eventual separation, both were very good candidates to become the next Dragon Diva. Since Teto came from a less prestigious family than Meiko, she was the one who ended up being chosen, even though, had social classes not factored into the equation, Meiko would have been the more likely candidate. Meiko urged Teto to refuse her burden, to run away, to do everything in her power not to become the next Diva. Unfortunately, as Teto knew, if this were to happen, the mantle of the Diva would fall, without question, on Meiko herself, so Teto chose to accept her fate, despite the grim future that she knew was awaiting her. To this day, even after Teto's death, Meiko blames herself for the sacrifice her friend made for her, finding solace only in the grief of her loss, and the anger at the culture of dragonism for causing it. During their fight, Meiko realizes that Len is just like her, in that he only wants to rescue his sibling, and Meiko would have done exactly the same thing if she had the chance. Meiko turns her sword to Luka, realizing that she lied to her, and Ruko intervenes. Ruko is another one of Luka's hired minions.
We go to Gakupo, locked in his room with a guard at the door, while he thinks about his past. He is freed, then, by a smiling Kaito. Kaito is a traveling clown who also seems to double as a mercenary, given his apparent fighting ability. Despite reports of an image of what seemed to be Kaito leaving, uninjured, from the party's fight with Miku at the end of the second video, most agree, upon further inspection, that his black-and-white blood-covered picture is meant to convey his defeat, just like those of Meiko and Gakupo. Gakupo and Kaito join up with Len and Meiko, and fight their way out of the castle. Then there's a "travelling" sequence, where Len's party (sure looks like a fantasy RPG, doesn't it?) wanders the realm, searching for the dragon's cave. Gumi makes a cameo, and if this WAS a video game, it looks like she would be an NPC (non-playable character).
Luka mobilizes her troops, sending them after our heroes. Seeing that the royal soldiers are trying to arrest the quartet, and because they are afraid of what will happen if the cycle of dragonism is broken, the villagers turn against Len and company. Len sees a small boy protecting his little sister from them.
Though it has been the fate of all Dragon Divas to eventually die of exhaustion, Rin, alarmingly, appears to be weakening at an accelerated rate, much faster than any Diva before her. When Len senses this, due to their weakening connection, and mentions it to Gakupo, the scholar tells Len that all Divas are made up of light and darkness, and surmises that, because of Len and Rin's connection as twins, the light and darkness of their souls is not distributed equally. Without a proper light-dark balance, Rin is singing and dancing her life away far more rapidly than she should be, making it all the more urgent that Len's party reach her in time.
Finally Len, Meiko, Kaito and Gakupo arrive at the dragon's cave. However, first, they must get past Miku, who is not about to just wave them on through. She summons some shadow-beasts, and easily defeats everyone in Len's party (and guess what? YOU HAVE NO PHEONIX DOWNS) Len especially gets pwned, *insert Miku's creepy laugh here* and we get some backstory on Miku. A flashback shows a group of dragonism priests putting the sinister-looking mask on a screaming and crying Miku. While Len is unconscious, a beautiful singing duet takes place in his mind with Rin and himself. Len wakes up, and takes Miku by surprise. He breaks her mask, seemingly breaking the spell that had been controlling her. He runs past her, into a bright light, where the silhouette of Rin is waiting...