For a variety of reasons, mastering the Japanese language is a Herculean task for non-Japanese people. Even if you’ve passed the highest level of the Japanese Language Proficiency Test, JLPT N1, it doesn’t necessarily mean that you can communicate effectively in Japanese to a Japanese person. This is because passing the JLPT N1 prepares a non-Japanese person for communication in a business Japanese environment. The things you study for the test might be sufficient for business purposes, but communication on a more personal level is a totally different ball game.
Knowing when to use the polite, casual and respectful/humble forms is of course important, but there’s one area that is just as significant – 「若者言葉」“wakamono kotoba” . Literally, it means “young people’s words”. The closest English translation for “wakamono kotoba” is “slang words”.
The Japanese language has undergone an evolution of sorts over the years, and it is not uncommon to hear young Japanese people (mainly from children to adults in their early 30s) use officially incorrect Japanese in conversations. A good example is the usage of the adverb 「全然」“zenzen” (~at all). According to the grammar rules, “zenzen” must always be accompanied by a negative clause. E.g. 「全然関係ない」“zenzen kankeinai” (“it’s none of my business at all”), 「全然分かりません」“zenzen wakarimasen” (“I don’t understand at all”). However, it is common to hear Japanese people use it with a positive clause. E.g. 「全然大丈夫」“zenzen daijoubu” (“It’s absolutely okay”).
The Japanese are known for inventing short forms of foreign loan words to make life easier and convenient for themselves. 「コンビニ」“Konbini” is a very good example of the shortened form of “convenience store”. Their own language is not spared this butchering of words.
As every Japanese learner knows, the passive form of Group II verbs ends with「～られる」“~rareru”. However, it is common for many Japanese people to omit the “ra” in conversations. So 「食べられる」“taberareru” (is eaten) has become 「食べれる」“tabereru”, 「見られる」“mirareru”(is seen) has become 「見れる」“mireru” and so on.
Most commonly heard, usually from girls, is 「きもい」“kimoi”, which is a corrupted version of 「気持ち悪い」“kimochi warui” (disgusting). 「うるさい」“Urusai” (noisy, irritating) is replaced by 「うざい」“Uzai”. The list goes on and on.
It’s important not to mix up such “wrong” Japanese used by young Japanese people with the “wrong” Japanese used in anime and manga. The language used in these media forms is exaggerated, and this is done deliberately. In particular, extremely strong expressions for “You” such as 「てめえ」“teme” and 「貴様」“kisama” that are often used in anime and manga should be avoided. Furthermore, the furigana written above kanji in manga may not be correct. Again, this is done on purpose. Therefore, learning Japanese from anime and manga is not a good way of improving your Japanese ability. As the language used is improper, you won’t learn real Japanese. On the other hand, it’s not an evolved form of Japanese either, so it’s not the norm to use it in real life – you’ll get less-than-positive reactions from your Japanese listener if you do. So using anime and manga language in a real life situation is a definite no-no… unless you want to be a comedian.
Non-Japanese are usually spared the pitiful, exasperated, “You’re stupid” or “What a dinosaur!” look reserved for other Japanese people, in particular the older ones, who do not know such “wakamono kotoba”. But if you have the chance to talk to young Japanese people, using or at least understanding the language that young Japanese use can help forge closer, more personal ties with them. On the other hand though, since such language is deemed improper, speaking it to older Japanese people will likely get you disapproving looks, so be sure to use it with care.