User blog:Dinodeclan/Villains for the series

I've been thinking. What would be the perfect antagonist for the series. I'm thinking kind of like a group of demon-like creatures born and feeds off of despair and sorrow known as "D5" the D stands for darkness and despair, whose leader was a former idol wanted to plunge the world in despair, but was actually brainwashed by D5 as their cover. They're kind of like the Deadly Six from Sonic Lost World. But they still get defeated by Yume and the others in the end. By a song and a rainbow appeal. What do you think would be the perfect main antagonist(s)?