Reviews by Brian D. Franke
Japanese: The Spoken Language series
I'd say you can't do better than "Japanese: The Spoken Language"(3 volumes) by Eleanor Harz Jorden and Mari Noda. These books are what I used, and to me they really get to the core of understanding Japanese grammar. As a bonus, there is also a set of listening tapes that goes with the books, and a videotape as well. My advice - DON'T NEGLECT THE TAPES! They are your only hope for ever understanding what is said to you without spending considerable time in Japan.