I just don`t get it when people say that Japanese and Chinese are dialects/related. And those who makes this kind of ill-informed claim are Chinese who can`t even hold an elaborate conversation in Japanese (i.e does not know Japanese). And don`t start claiming that you know Japanese if you can only manage sentences like "watashi wa otoko desu".

Now let`s see. I`ll make a preposterous statement in the same likeness too. Malay and English are dialects and are related. Why? Because both languages uses ABC in their writing systems and they both share a lot of vocabulary for e.g "produktif", "komputer", "sains" and so on and so forth. Oh ya and to make it even more absurd, let`s just ignore the fact that the two languages have anything in common only because of the long contact throughout history between the peoples speaking these two languages. Come on man...have you even done any research regarding "Sprachbund"? Hope you learn something from here http://en.wikipedia.org/wiki/Sprachbund

Japanese is in Japonic languages under Altaic language family. Japanese language have similiarities with Mongolian, Manchurian in terms of grammar, but high volcabulary similiarities with Chinese because of most vocabulary of Japanese language is based on loanwords from Chinese language they imported during Sui, Tang, and Song dynasties.

Chinese language is under Sino-Tibetan language family. Some Chinese can't learn Japanese well because of word order. Japanese language is Subject-Object-Verb, while Chinese language is Subject-Verb-Object. While Japanese language is not as flexible as Chinese language because Chinese language is isolating language, Japanese language is agglutinative language under synthetic language group. That means Chinese language do not have any inflection and tenses, while Japanese have.

Japanese kanji readed in two forms, kunyomi and onyomi. Onyomi is based on reading of Tang people and Wu people (Shanghainese and Hangzhou-ese). Some Chinese even confused when writing Chinese simplified characters instead of Japanese Kanji for some characters, which only used in Japan.

If want learn Japanese, learn Japanese through Japanese lingual habits, if learn through Chinese or any other lingual habits, it will end up suffering, except Korean, because these two language have very similiar grammar system. I have friends asks his Japanese teacher for what is the meaning of "wa", "wo”， “de", "dewa", "ja"... I think all of these can't be explained in Chinese, it only can learned through language experience.

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Added on September 16, 2010, 7:31 am

Kanji is based on Chinese characters, but there are Japanese exclusive Kanji also, created through Chinese character creation method.

Japanese civilization have two origins, one is local called Jomon civilization, another one is foreign, I forgot what is the name, is based from Choson peninsular residing in western Honshu and Kyushu. Modern Japanese is blend of Turkic blood and Chinese blood. From linguistics, Japonic languages are set into Altaic languages and share similiarities with Mongolian and Manchurians. Japanese people have archeological artifacts to prove these. While there are quite number of Chinese immigrants since Han dynasty, which some surnames can tell they are Chinese descent like Hata, which is descendant of special envoy of Shih Huang Ti of Ch'in dynasty sent to Mount Horai to find him elixir of life. Branch houses of Hata includes Haneda, Chosokabe, Kawakatsu, Jinbo, Koremune, etc.