I dont think he needs to leave bellator. He should stay and defend that belt and have them build the organization around him.
That or go back to Japan. He doesnt have many interesting fights in the UFC (take BJ out and the division is really weak) or any other US organization at that. Doesnt really make sense to go back to Japan bc he did fight Hansen, Aoki, Kawajiri...That is why I say stay at Bellator. Thought he would probably make the most in Dream