I've managed to dig up TLDR of drama behind the lawsuit on 5ch (aka 2chan): Kaida Haru organized a mixed gender Lethal Company collab with two Niji girls (https://www.youtube.com/watch?v=LJUclSYc8sU), which triggered female unicorns to the point where they spammed his twitter feed and tags, even trying to get Kuzuha involved to get him to kneel

Main rrat: Haru received death threads IRL similar to Vox, but culprit(s) weren't caught so he decided to file lawsuit against everyone through Anycolor (so he doesn't doxx himself in court papers)

That's all I could dig up with google translate