This book is suitable for learners who want to study, review and learn intermediate Japanese grammar. It will give you some Key Sentences, Formations, Example Sentences, detailed notes, explanations, differences and other infos that you can't even find online! The only downside is that this book is a bit expensive, but other than that, I think it's a great book! For learners who want to study intermediate grammar, this book is definitely for you!
Can be used as a reference for studying Japanese level N3 and above. Most of the grammar are not necessary to pass N3 but there are there for you to digest and learn as backup. If you wish to stop once you finished N3, then having this one would be perfect for you.