Diamond

""She got a Diamond and then the govenment came and then... Don't ask.""

Yuuki, walking to school one morning, finds a girl in a tree, trying desperately to reach a shining red thing right at the top. Yuuki decides to help her, being a Chivalrous Pervert, and together they end up receiving what can only be described as a "Diamond".

Later, Government Workers, kind of like The Men in Black, take both Yuuki and the girl, Kyoko, into custody and explain that the "Diamond" was one of three magical artifacts said to have been lost by the Ice Prince, placed in the human world so the vicious Fire Prince would get hold of them and try to destroy the world, and that they had also taken in four other teenagers who have some connection to the other two Diamonds.

Then, they were given a Sadistic Choice: Either they kill them and erase the memories of everyone that ever knew them, or they join the government to stop the Fire Demons from taking the Diamonds, which are filled with an "Unknown Power". Of course, they choose to join up, resulting in a bunch of odd occurances.

Tropes found in this work:

 * A Girl And Her Diamond
 * Action Girl: Kyoko, Mariko and Kazuko are this in spades; cute girls who also kill demons on a daily basis.
 * Aerith and Bob: Some occurances of this come up, such as the Main Characters, Kyoko, Yuuki, Itsuki, Mariko and Kazuko, and some of the Subcharacters, such as Ruby and Sapphire, the twin princes.