During a visit to the National Library, Miaka Yuuki and Yui Hongo stumble upon a strange old book that casts a red light, sucking them inside its unfamiliar world. Upon arrival, the two encounter hostile slave traders and barely escape with the help of Tamahome—a powerful young man bearing a Chinese symbol on his forehead. But, a moment later, the red light returns and takes Yui away. Desperate to reunite with her companion, Miaka asks Tamahome for assistance. However, the situation escalates when the pair encounters the land's emperor, Hotohori, who believes Miaka is the foretold priestess of the kingdom's protector god Suzaku. By gathering the god's seven Celestial Warriors, the priestess can summon Suzaku and have all her wishes granted. Hotohori hopes this will save his country, and since it appears to be a fitting solution to the girl's problems as well, he convinces her to accept the role. Meanwhile, at the library, Yui realizes she has been brought back alone. Unable to intervene, she helplessly witnesses Miaka traversing through courageous trials as the mysterious book's heroine.

In the hollow Mysterious Planet, seven kingdoms co-exist, all of them lit by the Sun's Blessing from the Kingdom of the Sun, in the middle of the planet. The light of the core sun is necessary for the continued existence of all the kingdoms. Yet, something is causing the Sun's Blessing to weaken. If something isn't done, it will be the end of life in the Mysterious Planet. Fortunately, the twin princesses of the Sun Kingdom, Fine and Rein, have been endowed with the magic of the Prominence, and are looking for a way to fix things. (Source: ANN)

Following her grandfather's recent death, Hamaji Ooyama lives out her days on an isolated mountain hunting for food and caring for herself. One day, Hamaji's brother, an aspiring samurai living in Edo, sends her an invitational letter to end her solitary life and join him in the city. When she arrives, however, she is met with a grisly sight—the heads of six dogs displayed for all to see. These heads belong to the Fuse, a group of eight human-dog hybrids that have been terrorizing the people of Edo. Hamaji assists a strange man escape a group of assailants and makes it to her brother's house, where he asks that she help him collect the heads of the remaining two Fuse, as well as the Shogunate-sponsored bounty. But it is easier said than done—as the Fuse can blend into human society almost seamlessly—and the kind man Hamaji had just helped showed the Fuse's telltale signs.

In the year 2047, mankind discovered a rare metal ore called Gaimetal, which possessed a huge amount of energy, and mining for these strange metal ore begins all over the world. However, in 2075, humankind were been constantly attacked by Gaist, a race of metallic creatures whose bodies were encrusted with Gaimetal, thus forming the GCG (also known as Gaist Crusher Garrison), an organization tasked with dealing against the Gaist. In 2064, the GCG send out mankind's line of defense: the Gaist Crushers, humans who can wear a special Gaimetal armor called Gaist Gear, and battle the Gaist,as well as the threat opposed by a mysterious organization called Erasers. (Source: Wikipedia)