Of course I don't what breeds of chickens you have in Indonesia, but it looks like a mixed breed. And you never know how a mixed breed chicken is going to turn out. I don't know of any breed where the pullet/hen is bigger than a cockerel/rooster. If you are comparing him to a larger breed, of...
there is no such thing as "too small" to be a bantam. Many bantam breeds weigh under a pound.
Are you wanting to know what breed he is or just wanted to post about him?