Japanese vowels are "pure" sounds, similar to their Spanish, Greek or Italian counterparts. The only unusual vowel is the high back vowel /ɯ/, which is like /u/, but compressed instead of rounded. Japanese has five vowels, and vowel length is phonemic, so each one has both a short and a long version.
Some Japanese consonants have several allophones, which may give the impression of a larger inventory of sounds. However, some of these allophones have since become phonemic. For example, in the Japanese up to and including the first half of the twentieth century, the phonemic sequence /ti/ was palatalized and realized phonetically as [tɕi], approximately chi listen (help·info); however, now /ti/ and /tɕi/ are distinct, as evidenced by words like paatii [paatii] "party" and chi [tɕi] "ground."
The r of the Japanese language (technically a lateral apical postalveolar flap), is of particular interest, sounding to most Europeans' ears to be something between an l and a retroflex r depending on its position in a word.The syllabic structure and the phonotactics are very simple: the only consonant clusters allowed within a syllable consist of one of a subset of the consonants plus /j/. This type of clusters only occurs in onsets. However, consonant clusters across syllables are allowed as long as the two consonants are a nasal followed a homo-organic consonant. The consonant length (geminates) is also phonemic.