JacinLarkwell - did you raise those birds together, or were they all strangers to each other when you put them together?
I think that the fact that the op is new to chickens, putting strange chickens together, that the size difference may cause trouble. However, I do not have experience with that type of flock. I will be interested in your suggestions.
They were strangers. I got the Japanese last year from a 4Her and after quarantine just stuck then in the coop at night. They were adults and my hens at the time were adult