Linguistic terminology for Japanese is simply not fixed. So you can find (proper printed) books (PPB) saying Japanese has zero, one, or two sorts of adjective, for example. (Wikipedia says three, but it isn't a PPB.)
"Postposition" is a pretty standard term for any sort of "functor" word coming after (or, equivalently, forming the end of) a noun phrase. So particularly when this "functor" word closely resembles a preposition (in English for example) except for its position, then it is very hard to see how you could object to calling it a "postposition". In particular, ～から and ～へ ("to" and "from"). Equally, the particles sometimes called "case particles" (が for nominative, を for accusative, に for dative) can also be called postpositions. FWIW, Wikipedia simply says "postpositions, also called particles".
So the answer could be that there is no clear meaning to the question. But it could also be (if you are really asking "how does Japanese grammar work") to say that, yes, all functor words in Japanese come after the phrase they modify, because Japanese is relentlessly left-branching. If a verb has two arguments (e.g. the verb to read in "He read [1]his daughter [2]a book") then each argument will be followed by a particle, which forms a "hook" showing how the argument. So [1] is 'musume-ni', where 'ni' indicates "dative", and [2] is 'hon-wo', where 'wo' indicates "accusative".
My terminology is likely not to be the same as anyone else's, and romanisation is intended to clarify rather than to follow a particular standard (e.g. I distinguish the accusative を as 'wo', but it is usually transcribed 'o').
