As regards sentence structure, German is strikingly similar (much more so than Chinese). So was Classical Latin. If you are seriously interested, you can consult S+O+V, O+V, "head-last", "postpositions", and other relevant features in "The World Atlas of Language Structures" at http://wals.info/ Best. L

No! Japanese sits by itself as a language group. The closest similarity is Korean, but the two are not related.

I don't know maybe the Ainu language... maybe... Of course Japan shares its writing Kanji with China. I've also heard that Korean and Japanese sound similar although I have not verified this myself. I think Japanese is a highly compatible language for English speakers. The sounds are easily pronounceable for English speakers with open minds. But I don't think there is any language quite like Japanese. In my studies of both languages I have found carry over words from Mandarin and also from many languages including English Portuguese and Spanish. Katakana itself is devoted to incorporating every foreign word Japanese adopts. So I would say that Japanese may eventually be like every language at once.

i think turkish is similar because S + O + V system, same type adds, same type verb conjugation, pronounced as it written like japanese but not similar writing system using latin alphabet

Since the asker's question was "Are there languages which are SIMILAR to Japanese"?, and NOT "Are there languages historically-genetically related to Japanese?", Eliot's original comment, and now his much longer one, are perfectly IRRELEVANT. Why "similar" should mean in Eliot's English "genetically related" is a mystery, but the two expressions are completely different and easy enough to distinguish, and why he should believe he can make his idiosyncratic usage prevail here just by accusing other people of ignorance or of not having read any "proper books" (please note the source of his "erudite" contribution!) is simply incredible, :-). What arrogance! I hadn´t seen anything like this in years, :-).