I also don't follow Japanese politics very closely and am just now skimming. A lot of people have posted a ton of other damning stuff but he is generally described as an ultra right nationalist and Steve Fucking Bannon apparently called him "a great hero to the grassroots, the populist, and the nationalist movement throughout the world", and even said he was Trump before Trump.

....that's pretty damning just on its own.

Edit: LMAO...his bio reads more and more like a demons resume the deeper you go.