Theme: Long ago there existed ancient demons in the universe of YuEmEl. These demons collected creatures called kodez. The demons put their kodez in battle against each other to determine which demon was the most powerful. Such demon was granted the title, demon lord.
These kodez each had level rankings based on their skill and abilities. The stronger they were, the higher their level.
Sadly, during the great tragedy of Y2K, the universe YuEmEl fell into chaos and all the demons were banished alongside their kodez.
The whereabouts of the demons are unknown to this day, but the same cannot be said for the kodez. These kodez were sent to Earth in the form of what we know as QR codes. The kodez can now be collected by Earthlings all around the globe, and they are kept in mobile devices known as 'Smartphones'.
Left masterless, these kodez are eager to be collected once again, in the battle to grant their owner the noble title of Demon Lord.