Japanese word order is classified as Subject Object Verb. However, unlike many Indo-European languages, Japanese sentences only require that verbs come last for intelligibility. This is because the Japanese sentence elements are marked with particles that identify their grammatical functions.
The basic sentence structure is topic-comment. For example, Kochira-wa Tanaka-san desu (こちらは田中さんです). Kochira ("this") is the topic of the sentence, indicated by the particle -wa. The verb is desu, a copula, commonly translated as "to be" or "it is" (though there are other verbs that can be translated as "to be"), though technically it holds no meaning and is used to give a sentence 'politeness'. As a phrase, Tanaka-san desu is the comment. This sentence loosely translates to "As for this person, (it) is Mr./Mrs./Miss Tanaka." Thus Japanese, like Chinese, Korean, and many other Asian languages, is often called a topic-prominent language, which means it has a strong tendency to indicate the topic separately from the subject, and the two do not always coincide. The sentence Zō-wa hana-ga nagai (desu) (象は鼻が長いです) literally means, "As for elephants, (their) noses are long". The topic is zō "elephant", and the subject is hana "nose".
Japanese could be considered a pro-drop language, meaning that the subject or object of a sentence need not be stated if it is obvious from context. (Note however that Chomsky's original formulation of this category explicitly excluded languages such as Japanese.) In addition, it is commonly felt, particularly in spoken Japanese, that the shorter a sentence is, the better. As a result of this grammatical permissiveness and tendency towards brevity, Japanese speakers tend naturally to omit words from sentences, rather than refer to them with pronouns. In the context of the above example, hana-ga nagai would mean "[their] noses are long," while nagai by itself would mean "[they] are long." A single verb can be a complete sentence: Yatta! "[I / we / they / etc] did [it]!". In addition, since adjectives can form the predicate in a Japanese sentence (below), a single adjective can be a complete sentence: Urayamashii! "[I'm] jealous [of it]!".
While the language has some words that are typically translated as pronouns, these are not used as frequently as pronouns in some Indo-European languages, and function differently. Instead, Japanese typically relies on special verb forms and auxiliary verbs to indicate the direction of benefit of an action: "down" to indicate the out-group gives a benefit to the in-group; and "up" to indicate the in-group gives a benefit to the out-group. Here, the in-group includes the speaker and the out-group doesn't, and their boundary depends on context. For example, oshiete moratta (literally, "explained" with a benefit from the out-group to the in-group) means "[he/she/they] explained it to [me/us]". Similarly, oshiete ageta (literally, "explained" with a benefit from the in-group to the out-group) means "[I/we] explained [it] to [him/her/them]". Such beneficiary auxiliary verbs thus serve a function comparable to that of pronouns and prepositions in Indo-European languages to indicate the actor and the recipient of an action.
Japanese "pronouns" also function differently from most modern Indo-European pronouns (and more like nouns) in that they can take modifiers as any other noun may. For instance, one cannot say in English:
*The amazed he ran down the street. (grammatically incorrect)
But one can grammatically say essentially the same thing in Japanese:
Odoroita kare-wa michi-o hashitte itta. (grammatically correct)
This is partly due to the fact that these words evolved from regular nouns, such as kimi "you" (君 "lord"), anata "you" (あなた "that side, yonder"), and boku "I" (僕 "servant"). This is why some linguists do not classify Japanese "pronouns" as pronouns, but rather as referential nouns, much like Spanish usted or Portuguese o senhor. Japanese personal pronouns are generally used only in situations requiring special emphasis as to who is doing what to whom.
The choice of words used as pronouns is correlated with the sex of the speaker and the social situation in which they are spoken: men and women alike in a formal situation generally refer to themselves as watashi (私 "private") or watakushi (also 私), while men in rougher or intimate conversation are much more likely to use the word ore (俺 "oneself", "myself") or boku. Similarly, different words such as anata, kimi, and omae (お前, more formally 御前 "the one before me") may be used to refer to a listener depending on the listener's relative social position and the degree of familiarity between the speaker and the listener. When used in different social relationships, the same word may have positive (intimate or respectful) or negative (distant or disrespectful) connotations.
Japanese often use titles of the person referred to where pronouns would be used in English. For example, when speaking to one's teacher, it is appropriate to use sensei (先生, teacher), but inappropriate to use anata. This is because anata is used to refer to people of equal or lower status, and one's teacher has allegedly higher status.
For English speaking learners of Japanese, a frequent beginners mistake is to include watashi-wa or anata-wa at the beginning of sentences as one would with I or you in English. Though these sentences are not grammatically incorrect, even in formal settings it would be considered unnatural and would equate in English to repeatedly using a noun where a pronoun would suffice.
source : wikipedia