Having to look for several hours for DBs and invoque an eternal dragon that bends reality at will to change a so tiny detail such as your aura colour is … maybe a bit harcore ? It’s like going to the Niagara waterfalls to fill up a glass of water.
Especially knowing that when you create a ki blast you can choose the colour. I don’t see then why I can’t change the coulour of my aura as easily.
So there could be in the ki techniques tab a box that allows you to change the colour
But it wouldn’t be free either, it should cost some TPs, like [player’s level]*100.
Here you are, just a quick thought.