Here is Maya’s millenium pao.
I guess , katey system is similar.
Well, I like category system , only when we talking about person list but if we are talking about objects I guess major and ben is better. (It’s my personal opinion, everyone has their own mindset.)
Different categories - Pokemons, disney princess, Marvel , comic character, anime, series, serials, cartoons, famous people, mythology character, video game characters, history …
You can use that 10 list for your main category and make a category System.
I have one question because you already tried that system.
I know many characters from different categories.
Currently I have 3 digit letter system and I wanna add and use that character in my system (otherwise they will be useless)
Option 1 - Add that all characters by letters.
And use them in my current letter system.
Option 2 - make a list of characters by assigning them a category.
It will be easier for me to remember 9 is anime.
So 900 - 999 (will be anime)
300 - 399 (marvel)
And so on…