My father works for a japanese oil exploration company, and has been for about 25 years.

He just got back from a trip to give a presentation in Japan...first thing I hear when he gets back is how badly racist the Japanese are.

I know it's just an anecdote...but it's been his experience in general over the years.

That is probably enough info to ID him- you may want to edit that in case of unintended negative repercussions for him...

Fair point, I've updated it.

I've been reading Yakuza: Japan's Criminal Underworld recently (fascinating read about the yakuza's history in Japan) and it mentions that a large percentage of Chinese and Korean immigrants turned to gang life because they were considered a lower caste, like the burakumin (Japan's untouchables). Maybe things have changed since the 80s-90s?

Not drastically, it seems: https://en.wikipedia.org/wiki/Ethnic_issues_in_Japan

There are several foreign workers but they mostly work for established international companies with offices there. Few of these companies are Japanese (people do work for Japanese companies but usually outside Japan). It's not only about xenophobia, Japanese work culture is deeply hierarchical and seniority-based (the person who's been in the company the longest gets to run it, regardless whether they're any good at their job or not). Companies change their policies very slowly. They fear that foreigners would not understand this culture and try to disrupt it, for good or bad.