The bottleneck at my entry this month in KIX was absolutely Passport Control because, after the fingerprint station, you have to pick one of 15ish lines to stand single-file in. If your line gets stuck because of some sort of person who gets rejected or needs to be questioned, everyone in your line gets delayed. I have no idea why they don’t have one line and then helpers to usher each person in the single line to an open desk - that seems like it would be far more efficient.