I have NEVER found the outbound immigration line to go all the way to the back wall, however (fortunately).
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It's out of control during school holidays and weekends. I can understand Russian and Chinese authorities harassing their own citizens but I can't understand why the Japanese subject their own citizens with the same scrutiny as foreign travelers exiting the country.

And another thing, if a bunch of Koreans are ahead of you in the immigration line, you're in for a longer wait.