I wouldn’t call him imperialist, but he repeatedly denied WW2 Japanese war crimes (in particular the Nanking massacre and the use of Korean ‘comfort women’). This is the rough equivalent of a German Chancellor denying the Holocaust.
I wouldn’t call him imperialist either. I think he was a pretty decent leader for Japan. He wasn’t murdered for his politics, but because of his religious affiliation.
It wasn’t just religious affiliation. He, and others in the LDP, protected the Moonies in return for their political support. It was very much a political issue (separation of church and state).
LDP is a conservative party, with members ranging from centre-right, far-right to ultra-conservative. Don’t be fooled by the name of the political party. Japan is notorious for it’s 1955 System - also known as the “one-and-a-half” party state. And about the imperialist comment - as is obvious from the party dominance - most of the LDP members deny, and don’t teach their own history to their citizens. History revisionism is the tool of imperialism - and no one does it as well as the Japanese government.