Ansonsten Kanji != Hiragana, Katakana
Kanji sind die "importierten" Zeichen aus China.
Ein Kanji hat eine Bedeutung und dementsprechend auch unter Umständen mehrere Laute.
bsp: watashi - 私
Japan has made many modern words (the combination of two kanji usually) since Meijirshin (Meiji Reformation), then it exported most of new words, for example 科学(kagaku,science),医学(igaku,medicine),中国(chuukoku, China), 帝国主義(teikokushugi,imperialism), 共産主義(kyousanshugi,communism) and so on, besides, Japan has imported a large number of loanwords(外来語 kairaigo) from English, German, Dutch, French, Spanish,etc.,
http://de.wikipedia.org/wiki/Gairaigo, they are all katagana, for example, エロチック is erotic in English, エロ for shot as anime-manga slang, アルバイト is Arbeit in German, now バイトisアルバイト for shot, it's used as part-time in Japanese media or anime-manga ordinarily.
Other,
ドイツ語から日本語への借用 (loanwords from German).
More and more Japanese loanwords are increasing instead of old kanji words, especially for any knowledge field, thousands of kanji is just a small problem, but Asia people have to face difficulty at endless loadwords when they are learning Japanese, so some people think that they are able to read Japanese news and article if they just complete thousands of kanji, no, they are wrong, the loanword is one of the biggest feature of Japanese literature.
Sorry that I as an foreigner join the discussion, typing english more quickly than my bad German... =.= if my opinion is incorrect, anyone can correct me..

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Wenn du auswandern willst, musst du die Sprachkenntnisse mit dem JLPT-Test nachweisen. Und für eine richtige Arbeit, brauchst du den höchsten Level.
How is auswandern? work? study abroad? emigrate? if you want to emigrate in Japan, you should get 外国人永住許可 (Gaikokujin Eijyuu Kyoka, similar as green card in USA),
http://www.moj.go.jp/ONLINE/IMMIGRATION/online_immigration_16-4.html
or 帰化 (Kika, naturalization )
http://www.moj.go.jp/ONLINE/NATIONALITY/online_nationality_6-2.html
永住許可申請とは、日本に住んでいる年数については、特に決まりはありませんが、日本人の配偶者で3年以上、一般で5年以上が目安のようです。
You are eligible to Eijyuu Kyoka or Kika after you live in Japan for five years or marry Japanese for three years with legitimate income and tax at least.
Besides, JLPT-Test is just a certificate of language ability, referenced to study abroad usually, in Japan undergraduate needs 2 level, graduate needs 1 level, else, J.Test (実用日本語検定) is much harder than JLPT,
http://j-test.jp/xp/modules/tinyd10/content/index.php?id=11 it has level A-D (Middle to advanced) and level E-F (Beginners), in exam listening test is 50% and other is 50%.... J.Test is used for working and business.
Another third one is BJT (ジェトロビジネス日本語能力テスト)
http://de.wikipedia.org/wiki/JETRO-Test, at present there are three Japanese tests for foreigners.