The other thing I would mention is that even if you learn standard Japanese anime is going to have a huge amount of slang and idioms.

The good thing is that, as in most modern Japanese, it will also have a huge amount of English loan words. The pronunciation may be slightly different, but you can recognize things like “hambaagaa” or “paypaa”.

Of course, sometimes it can go too far, like when I lived in Japan in the 90s and on days when they encouraged people not to drive themselves, it was a “No mycaa dayi” (“No my car day”).