Reddit mentions of The Structure of the Japanese Language (Current Studies in Linguistics)

If you are interested in a book of Japanese linguistics this is a good book and another good one is right here.

These are linguistics books though, so a background or knowledge there will help. As far as etymologies go, while interesting, I don't really think they do all that much for actual studying or understanding. As an example, for a learner of English, learning that "you" is the dative case of ġē, was originally a plural, and the polite version of you isn't really going to do anything for learning what it means now or how to use it.

As supplemental reading, I quite enjoyed The Structure of the Japanese Language, fwiw.