Each character in Disgaea 5 has multiple colors and sub classes to choose from. Some of these are requirements for a quest, and others can be used to unlock new recruits. Check out How To Change Your Color And Sub Class In Disgaea 5 here!
In order you to change your color you will need to go to the Assembly. The Assembly will be unlocked during chapter 2 I think, it’s pretty early. Once you are there, pick the character you want to change and select change color. You can also do a quest to get more colors to use and pass a bill to let you do custom colors later. For non main characters, fighters, mages, etc, the more stars you have the more extra colors you get.
You can also set a sub class to any of your main characters at the Assembly. This is very helpful for mastering a class for quests and new recruits. You can assign any class to any of your main characters and it will be upgraded. The higher the star rank for a new recruit, the higher their base stats and potential. This is the only way I got through all my new unit quests. Christo can use Demon Solace for any magic class and get upgrades extremely fast.
Changing color is just a little something you can do to liven things up a bit. Check back soon for more Disgaea 5 guides!