Some of their establishments(diners to brothels) openly display "Japanese Only; No Foreigner Allowed in"...
They might have had some bad experience with some ass*ole aliens though.
While many other shops started to display notice in various languages including English.
And migrant workers from SE Asia in Japan are sharply increasing(in retail, hotel, food & beverage sectors), making up their rapidly aging workforce.
In recent years, they dramatically relaxed the requirements to be Eligible Foreign Workers.
No longer need to be the Professionals with fine academic backgrounds, unlike yesteryears.
Now shop assistants and construction workers can come to work in Japan.
Even though it often comes with the Rip Off practice by the Visa Agents on both ends(their home country and destination). Making these poor people pay hefty fee, for arranging their legal status in Japan.
Said to be no less than U$10000-15000; eye-popping amount to them
In other words, they usually owe the Big Debt, before they start to work there(and gradually pay it back as they work).
It is mostly their own kinds who prey on these migrant workers...