Blue Dragon, on TV Tokyo
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This is based on a video game, which I've never played. Anyway, long ago, there was a great battle between the forces of Light and Darkness. And the Darkness was finally defeated by the Seven Soldiers of Light, who possessed the power of Shadow. That is, their shadows could like, come to life as these big sort of monsters or whatever. I guess. Though the creatures seem to remain attached to the humans, like shadows, but... otherwise move around and battle and have their own identities, personalities and whatnot. Though they seem to draw strength from the humans to which they are attached. Anyway, after they defeated the Darkness, the Seven Soldiers sealed away the power of Shadow.
However, now the evil King Nene of the Gran Kingdom has found a way to artifically create the power of Shadow, which he's given to his servants to go out and take over the world, I guess. But there are two people, a woman named Zola and a boy named Jiro, who are trying to find and assemble the descendants of the Seven Soldiers of Light, to once again fight the Darkness. Um... the two of them both have Shadows (Zola's is Killer Bat and Jiro's is Minotaur), so they're already powerful fighters. And at the start of the series, they meet a group of kids, including a boy named Shu, who wants to travel around the world having adventures and become a Knight Master. And it turns out he also has a Shadow, which is the Blue Dragon, though he wasn't aware of it until now, and it takes him some time to learn to control the power.
Anyway, Shu and one of his friends, a girl name Kluke (who is obsessed with machines) leave their home, Talta Village, to travel with Zola and Jiro to find the others they'll need to fight Nene's forces. Before long they're joined by a little creature named Marumaro, a member of the Devee tribe, who has a shadow named Saber Tiger. And a little later, the group meets a girl named Bouquet, a member of the Rah tribe, who has the power to make herself invisible. (She ends up considering Shu her fiancee, though he doesn't feel the same.) She also has a shadow, named Hippopotamus, though he and Bouquet are no good in battle. But they're useful in other ways, like transformation. At first they don't let her join the group, but she secretly follows them and soon proves her usefulness.
Well, as the group travels, they have to battle various forces sent out by Nene, including plenty of shadow-wielders. Their greatest opponent is General Logi (his shadow is Valkyrie), and his Independent Flying Squadron, which includes Cynthia, Gilliam, Lemaire, Andropov, and Schneider (all of whom have their own shadows, of course). And at one point the heroes protect a man named Legolas as he heads back to his home of Jibral, where he delivers a document to his king. They also meet a Knight Master named Conrad, who inspires Shu. Meanwhile, Zola wants to read the Book of Origin, the original copy of which (the only one containing 7 extra pages) is kept in Jibral's library. But the pages are stolen before she gets a chance to read them. Also, it turns out Jibral had joined forces with neighboring kingdoms to oppose Gran Kingdom. They asked Zola's group to join them, but they had their own quest to complete, instead.
They infiltrate Nene's castle, but he and his shadow (Chimera), easily defeat our heroes, who only escape with Kluke's help. It turns out she has a shadow, herself, named Phoenix. Zola decides they need to find the Extra Seven pages (which she believes may teach them to make better use of their shadows). She also believes that the six of them are the descendants of the soldiers of light, which leaves just one more to find. Meanwhile, they get a master informant, Homeron, (or actually a small group of informants) to try to find the woman who stole the Extra Seven. Also, they learn that Jibral has been destroyed by Nene. The kingdom has apparently disappeared, so Legolas, who had once again briefly been travelling with our heroes, heads back home to see this for himself, as he can't believe it's true.
They eventually learn that the woman who stole the Extra Seven, Delphinium, gave the pages to General Logi. But they manage to get copies of the Extra Seven, with Bouquet and Hippopotamus' help. It takes some time to translate the pages, but once they do, it helps them learn what each of them has to do to increase their powers, so they can once again take on Nene (who Zola has learned is actually the seventh descendant of the Soldiers of Light!) Anyway, eventually Nene is defeated, but General Logi has his own plans, so even while our heroes celebrate, it's clear that their troubles aren't over. Meanwhile, Zola plans on another mission, but Kluke gets captured by Logi....
And that's all I can say so far. Cartoon Network stopped airing the series after episode 14, and Toonami Jetstream only got as far as episode 40. There are 51 episodes in the first series, and I haven't gotten to see the last 11. But there's also a sequel series, of which I've seen none at all. I really hope to someday see all that I've missed....