ushirou is a user on kamiyacho.net. You can follow them or interact with them if you have an account anywhere in the fediverse. If you don't, you can sign up here.
ブタゴリラは本名が可愛すぎるのが嫌で、自分から皆に呼ばせているという設定らしい
https://ja.m.wikipedia.org/wiki/キテレツ大百科の登場人物