In RPG Maker, you have something called "actors" which are the characters that the player controls.
All actors are grouped into a "unit" called a "party". Actors can be added or removed from parties at anytime during the game. You can potentially have multiple parties in your game, depending on how your project is set up.
Each party has a leader. The leader is the actor that will be displayed while you're traveling on the map. By default, the leader is the actor that is in the first position of the party. So for example if you switched the positions of the first and second members of the party, the leader will change.
Now, what happens if you wanted the party leader to be someone other than the first person in the party? Maybe you want the leader to be a specific actor, but that actor doesn't participate in battle.
Or perhaps you wanted enemy troops to have a leader, and make it so that when the leader dies, the enemies will scatter and run away?
With this plugin, you can set up who will be the leaders of parties and troops, and build additional plugins on top of it that allow you to use these leaders to implement new game mechanics.
More information and downloads available at HimeWorks