Nanoorverse: The Islands of Nanoor if you haven't already guessed, is set on the Islands of Nanoor. (shocker!!)
The islands are on the modern earth, but they are in a special bit of the ocean that regular humans (or Noabil) cannot find. This cluster of islands are tied together by the magical current running through them, generated by a huge purple tree (Nanoor) situated in the middle of the largest island.
Some students who attend the RADAD (Royal Academy for the Defense Against Demons) are native to the Islands. They have been born there and have more of a purpley tinge to their skin. Usually these students are have a higher tolerance to pain, and more powerful abilities.
However, only a few thousand people live on the Islands (not including the students) so most trainees come from Noabil Earth. These are children born with prominent purple marks on a part(s) of their bodies. They are stolen away secretly at nighttime to be raised on Krassilif, a small island dedicated to educating the children and raising them until they are 12.
Then they will be enrolled into the Academy, where they will learn to fight and use their ability. This includes pain training, where the TDs (training directors) aim to strengthen their pain tolerance. Using you ability affects the area where your abilitem is (the area of purple skin where your power is drawn from) and causes pain, it could be as irritating as an itch all the way to as agonising as getting stabbed.
Most commonly, abilitems won't cause much pain, maybe a stomach ache, but the ability won't be incredibly powerful either. However, in rare cases students will have extreme power but suffer extreme pain. These people are put into an agency called Agency 222.
Why are these teenagers being trained? Well, it all started about 300 years prior, when a chunk was cut out of Nanoor. The tree tried to grow back as best as it could, but not before demons had escaped. You see, the only passage down to Crizel or the underworld is through the centre of Nanoor. When it was cut, they escaped into the Earth and wreaked havoc upon the Noabil. From that day forth, the Royals were informed and together they created the RADAD, the academy where ability wielding defenders of the Earth would be trained. They are then put into Agencies, and sent off on missions to protect the Earth and save its people from the vicious monsters that were once released.