Haato no Kagami
Plot (so far):

Sincerity arrives from another world (hereafter know as Green Earth) on the day Arisa is going to tell Fisher she likes him. Arisa sees Fisher kissing Sincerity and runs off, heartbroken. Fisher gets into a fight with Kenji over Arisa's heartbreak, but before Kenji can kick Fisher's butt Larou steps in to save him. Yet she's not interested in saving him but rather Sincerity, who's trapped in Fisher!

Meanwhile, on Green Earth an angel named Marchelle is captured by Rossy. Halfway across Green Earth, young Megan, feeling Marchelle's pain, rides to her rescue. Yet it is too late as Rossy turns Marchelle over to his lord Leo. Leo uses her to transported him, Rossy, and Marchelle to Earth Prime. Once there Leo has no use for Marchelle and wishs to dispose of her. However Rossy convices her to swear loyalty to Leo and that simple act stays Leo's hand, for the moment.

Using the Unicorn's Heart Leo transports himself, Rossy, Marchelle, and unbeknownst to him Megan, to Earth Prime. Megan still determined to find Marchelle uses her magic, but distracted by Kenji who looks like her dead brother the spell goes awry and leads her to Kenji.

Setting:

There are two Earths used for the setting of this story. One is much like ours (called Earth Prime); in the other Earth, humans struggle to survive in a word dominated by thick forests (hence why I call it Green Earth), wild beasts and magical beings.

Notes:

Magical beings - There are three races of magical beings on Green Earth: Unicorns, Angels (houou), and Dragons. The races serve to balance man and each other. Unicorns are the totally pacifist race, dragons are the militant race, and angels serve as a middle ground: some militant, some pacifistic, some neither.

The Unicorn's heart and Angel's reflection - According to Green Earth legend, these are two of the three sacred treasures given to the three magical races of beings (one to each). Most believe them to be childhood fables. It is a wildly popular myth that they're the source for all magic. However other myths surrounding them vary widely from tribe to tribe. Some tribes even hold that there may be a fourth treasure.

Knights - Knights are almost always human. This is how humans obtain magical powers. When they are very young, they are linked to a magical being. Only the strongest, most loyal, and smartest humans in a tribe become knights. The link works in the following fashion: the humans get some of the magical being's magic and the magical being gets someone that will protect them. To make sure the knights do their duty, the knights feel the same pain their beings do, bleed from the same wounds, and if the magical being dies so does the knight.