Lol, i swear i saw this idea but i can NOT remember, please tell me XD
YEEEEEE-
Many eons ago, the world was one continent, being ruled by one king and queen. Separate from Earth but nearby was the kingdom of the Moon, ruled by a Queen Regent until the princess came of age. Overtime, the people of Earth grew bitter towards the moon, as the people there possessed magical properties that Earth wish to take for themselves. Despite this, the princess grew curious about this place that mistrusted her, and began to visit the Earth's kingdom more and more often to sneak glimpses into their lives. She was caught by the prince, and despite the hate between their two kingdoms, a romance grew between them. Calamity struck however, when Earth's armies invaded the moon. The forces of the moon were quickly overwhelmed, and the princess captured. The prince pleaded with his mother and their forces to let the moon live, that they were not their enemies, but his pleas fell on deaf ears. The queen went to run the princess through with her sword, but the prince took that blow for her, dying in the princess's arms. Nearly an eternity later, the prince and princess were reincarnated on Earth as average high school students by day, crimefighting heroes by night, the memories of their past lives sealed away, returning to them only through dreams.
There's like-more, but that's the basic premise so yeeeeeeeeee-