If there is one thing you could kinda complain about in Eternum as far as the characters go, its that Chang really is nothing more than a comic relieve so far it generally feels kinda...tacked on. Like he was there right at the beginning of the game and it felt like he would be a lot more important than (at least so far) ended up being.
Yeah, he came up with the plan for the heist but even then we were more told that he made the plan, we didn't really see it.
Then again: I rather have more screen time for the girls then for Chang, to be honest.