Over the interwar period, fascist governments in Europe heavily promoted anti-Slavic propaganda. In Germany, they were labelled as Untermensch alongside the Jews, and in Italy, Slavic media, languages, and businesses were banned. During the war, the persecution evolved into an outright genocide, with millions of Slavic civilians and POWs being massacred in concentration camps.
Was there any similar attitude or activity against Slavs in Imperial Japan? I doubt that Japan ever found enough Slavic people to make something like the Holocaust possible, but were there other forms of persecution? Unlike Germany, Japan occupied part of Russia in the interwar period (see this and this). How were the Russians living here treated? Were Eastern European expats and POWs in Japan discriminated against because of their ethnicity?