Sword Calls

There's another timeline and universe, far from ours... In that universe, people have skills that are called 'Sword Calls'. Sword Calls are special abilities that can control the elements. The source of their power are swords, hence the name Sword Calls. There are a lot of them, but everyone is aiming to get the most special and powerful Sword Calls... There's also a villain called Kairox that has been a threat to humanity ever since he existed. That's why (mostly) kids are being trained to master at least 1 elemental Sword Call by the age of 21, so that they can fight in the war.