This is an absolute must have for every single person learning Japanese, period.
The Dictionaries of Japanese Grammar are the most recommended books from the Tofugu staff to learners of Japanese. There are three total, but the first book is a must have for all students, no matter what method they're using to study.
As Koichi said in his review of all three, "No single resource (nor any combination of webpages and resources) even comes close to what the Dictionary of Japanese Grammar book series has to offer."
While these are "dictionaries," they hold much more information than most people would expect from a typical dictionary. And the Basic book contains more grammar than most beginner textbooks and classes cover.
The dictionaries are in English alphabetical order, for easy reading. Each grammar point is a nice bright red and there is normal dictionary information like parts of speech, English meaning, and so much more.
For one thing, each grammar point is marked with a little number afterward, because the series covers every single possible meaning and usage of that one word or phrase. Beneath the entries are "key sentences" which are in Japanese (sometimes with furigana), with romaji and English translations underneath and marking of important parts of speech. Formations (usually common collocations), example sentences, notes, and more follow.
This is an absolute must have for every single person learning Japanese, period.
For more, check out our review!