I'm a little curious on why Hideyoshi calls Toshiie by his childhood name. Wouldn't that be incredibly offensive? Did the game say they knew each other as children?
Actually Hideyoshi doesn't even call him by name at first. He calls Toshiie with doggy/puppy (wanko-kun) the whole time. Later after they become close friends, Toshiie allowed him to use Inuchiyo.
This is discussed in their Main Route somewhere. I think it should be in the common route, but I don't remember exactly myself.
By realistic standards everything used in this game is very rude, so don't really pay much mind about the names XD Like, not even MC should be allowed to use Inuchiyo, childhood friends be damned, but hey.
Also, not visible in English, but in Japanese they're using -san and -chan honourifics, and both of those shouldn't have existed yet in that era.