It's been 500 years since 2 planets suddenly appeared near earth. Later people realized earth is also isn't in solar system. There is not any moon, new sun's color is also slightly red. But now you can say earth has 2 new big moon.
After these 2 planets appeared, it took 100 years to people from earth to make preparation to go to these planets. But what shoked earth's people was these 2 planets has humans and one of these planet was fantasy world where magic exist and other planet is murim world where martial arts exist.
It took many years to communicate, socialize and integration of civilization of three planets. There were even a war between murim world and the fantasy world. Amidst of all of this, earth became the bridge between 3 planets, because only earth had the technology to go to one planet to another.
Now it's been 500 years, now many things changed. There is a common language for 3 planets, all three planet's culture is now mixture of all of them. Every planets have same education system, have a common Stellar government. But competition between them is still very big.