Above thousands and thousands of miles away from Earth, a planet larger than Jupiter, colder than Mercury's dark side and more abundant than Earth itself, existed that no human scientist can discover - not even with the advance use of technology or the highly specialized satellites that man can invent.

Exo was no normal planet. It was located at the farthest side of the universe, if one can point its end. It was a shining, cyan planet, with a large crack on its middle that made it look like a newly-opened fortune cookie. There were thousands of moons that surround Exo, and it served as its source of light from daytime to nighttime. They don't need the sun to lighten their planet - their moon's unique lights were enough to cost them for a lifetime.

If Earth people were called 'humans', then Exo people were called 'exotics'. In human definition, the term exotic meant by "strikingly, excitingly or mysteriously different or unusual". Exotics definitely fitted this criteria. They were all strikingly attractive. One can't even point who was the fairest woman and the most handsome man in Exo; They were excitingly unique as well. They all have a small, glowing circular tattoo in a bright shade of cyan between their clavicles that differentiated them physically from humans. It was important for them to keep the tattoo glowing; Finally, they were all mysteriously and irregularly growing, with no definite time for them to age. Some doesn't even age after 20 years (in an Exo's timeline), and those lucky exotics can live longer than anyone. How was that possible? Then add this on the list of unanswered questions of the mysteries of Exo.

On the other hand, Exo was not a perfect planet. If Earth's United States and South Korea teamed up to go against North Korea and threatened each other with their ballistic missiles, then Exo has Exo-M and Exo-K who were in a state of war longer than anyone can imagine.

The EMs (Exo-M) were exiled exotics who did henious crimes in planet Exo. They were thrown in a deserted island on the farthest place of the planet.

And so the EMs seek for revenge... and it was revenge they shall get.

As the moons turned westward and nighttime fell, our story starts. Asteroids that were supposed to fall on planet Neptune shifted mysteriously on Exo instead. The fiery asteroids blasted crooked houses and injured thousands of exotics. Everyone sought for cover inside the enormous castle of GalaEXO, the place where the royalty king, queen, and their son lived.

In the midst of the chaos, King Iyo decided to transport his son, Prince Yeol to earth, together with his son's guardian, Mei.

Can Prince Yeol survive the upcoming challenges in this alien planet?