< NEN TYPES >
The unique about the Nen system is that you'll notice that certain classes are closer to others. This means that in your class you'll be the strongest, and in the two categories adjacent to your class you'll be the second strongest, the two farther away ones will be not very strong, and the one across from yours means you can't do anything with that field.
There is also a fun bit of world-building on how someone figures out their class of Nen. Firstly, they are born with it, so if you get a category you dislike you can't switch it, so you'll have to improvise. Watching a character have to figure out how to make the most out of a class they utterly detest is pretty fun. Secondly, you can take two tests to figure out what type of user you are.