Hitoshi Kunima is a common high school student. ("Shadow", who appears in Hitoshi's dream everynight, says Hitoshi is Gaia's soldier transmigrated. But, Hitoshi deny it emphatically.)
"Shadow" got impatient and appeared in the real world to persuade him to obey his destiny. But, the sublime mission: "'Gaia' with special ability controls everything, before human go to ruin with the world" was ignored by Hitoshi says "It's silly". "Shadow" took Seria Kidou, a friend from Hitoshi's childhood, as a hostage, and tries to awake Hitoshi to "the memory of his previous life", but Hitoshi saw easily that Seria is the main body of "Shadow". Seria knew that Hitoshi want to live as "Hitoshi Kunima", and gave up for the time being to persuade Hitoshi.
But, then, one of "Valhalla", wants to wipe out "Gaia" to keep the peace of the world, appeared and attacked Hitoshi and Seria. Sakura Souma, in the same grade with Hitoshi and Seria and one of Gaia's soldier, beat the "Valhalla", but by that, Hikari Ragou, the leader of "Valhalla" knows that where Hitoshi, Seria and Sakura are----
By the order by Hikari Ragou, the leader of "Valhalla", the attack by "Valhalla" stopped. But, the quiet didn't continue for a long time.
Akimitsu Mishima, one of very powerful soldiers of "Valhalla", wants the battle against strong enemies, and declared war against Hitoshi and his companies, ignoring the order by Ragou. By the persuasion by Shizuka Ayabe, Ragou's confidante, Mishima once withdrew. But, by Mishima's attack, Seria and Sakura knew that the "Gaia"'s ability of Hitoshi had already awoke.
The Master of "Gaia" contacted with Hitoshi who still deny the "destiny" of Gaia. And, some members of "Valhalla", who don't agree to the order by Ragou, attacked Hitoshi, Seria and Sakura in a hamburger restaurant. They escaped narrowly, then Hitoshi got home and received a letter. The sender is----Akimitsu Mishima.
By that Hitoshi and his companies(?) traced the truth and beat "Master", the battle between "Gaia" and "Valhalla" ended. They still have the ability of "Gaia" or "Valhalla", they need not to use the ability now and live in quiet.
One day, Akimitsu Mishima went to an art museum, and met a girl who says she is an eager fan of his sculpture. The girl, who introduced herself as Maya Katsumi, attacked mounted an offensive against Mishima by the ability like that of "Gaia" and "Valhalla". About that time, people had taken part in the battle against "Master" was attacked, one after another.
In all cases, there's people with ability like "Gaia" and "Valhalla", but are neither "Gaia" nor "Valhalla"---- It's can explain this situation to suppose that "Master", thought as to be dead, began to kill obstructive people: Hitoshi, Ragou and their company.
However, it's impossible to beat all assassins from "Master" who never appear. In minds of everyone (expect Mishima), uneasiness and impatience was growing----
The concluding volume of the series. What is the answer by each of them, to the temptation named "power"----?