You can check unknown words by dictionary. But how do you check grammar? 「基礎日本語文法教本 (Understanding Basic Japanese Grammar) 」is an ideal grammar reference book for basic and intermediate learners (JLPT N3, N4 and N5) . With this book, you can check and understand grammar easily as, besides the clear explanation, there's plenty of practical example sentences. 

In this book, One and Two are the introductory stages, Three and Four are the Expanding stages and Five and Six are the Advanced Stages. The Table of Contents is 12-page long and is very thorough. It shows exactly what grammar will be discussed on each page of the book with the structure written in Japanese and the meaning summarized in English. For example, 「いつ」on page 28. This is very useful as a reference book for grammar.

Other good points of this book:

• Simple explanation of grammar points

• A lot of example sentences, paragraphs and conversations 

• Great English translations into English (There is a Chinese edition too, if you prefer)

• It follows the grammar and vocabulary guidelines for JLPT N3, N4 and N5

• Furigana for kanji

• It containts a CD  

Please note that this book is not for self-study. Explanation of each grammar is too simple to learn new expressions without guidance of teacher. 

Students who need this book are those who:

• Need grammar reference

• Want to review the grammar they have learned in lessons

• Want to take JLPT N3, N4 or N5

To pass JLPT N2, its really important to have a deep understanding of basic grammar. But how do you review the grammar you've learned?

To do so, I recommend 「 短期集中初級日本語文法総まとめ ポイント20」. This reference book is not for beginners as the explanation might be too difficult for them. However, if you use this book after you have learned some basic grammar in class , this book will be easy-to-use and handy. 

This book consists of basic grammar, for example 1課　助詞　2課　「は」と「が」　4課 「て形」・「た形」　5課　動詞の活用と文型　6課　ふつう形　8課　申し出・勧誘　　11課　～ていく・～てくる　12課　他動詞と自動詞　13課　可能表現　15課　条件など　16課　授受　だれがだれに？　17課　使役　18課　受身・使役受身　19課　敬語　

It may seem a bit too much, but if you are taking JLPT N2 and feel nervous about the exam, before you sit for the exam, get a deeper understanding of basic grammar by this book! 

At bookstores, I have always been surprised at seeing tons of reference books of keigo (honorific expression) for Japanese natives. However, looking back at my teenage years, I've never spoken in keigo. After I graduated from school and started working, I learned that I should speak with my boss and clients in keigo. Sometimes, even people who are older than me spoke to me in keigo. Hence, I started to learn keigo. 

I think it's not so difficult to master keigo if you know what is keigo like and how to study it. 

To whom do we use keigo? It is not necessarily just towards our elders and betters, as commonly known, but also for certain strangers. For example, even the Japanese emperor talks to me in keigo, because we are not close at all. To pass JLPT or to communicate in Japanese, you don't need to speak or write in keigo but you need to understand and memorise some keigo. 

How to study keigo? To master keigo is to learn the expressions by heart in context. Please note that you need not only understand keigo but also grasp keigo vocabulary by heart.

I can recommend this book, if you really want to master keigo. After you master this reference book, you can use keigo better than Japanese teenagers!

Particles... this is the first thing you need to swallow to master Japanese language. You probably have learned /are learing particles, but you might feel confused about the grammar. There are some reasons that you might get confused. 

1) There is no substituon of particles in English and Chinese.

2) You might have a prejudice for particles

3) You have not learned particles systematically 

With regards to point 3, Japanese language teachers tend to teach particles severally. Of course, it is not culpable, because it's effective to learn particles bit by bit, and from easy ones. But I believe we should sort out and review particles systematically when you finish basic level. If you have passed JLPT N3, and are thinking of passing JLPT N2, please use this dictionary and review particles by yoursef. You don't need to read this dictionary from first page. At first, you can use it as a special dictionary for particles, and after you feel like sorting out particles that you have learned, read a chapter of certain particles. 

In some of my private lessons for advanced JLPT N2 students, I noticed that they are not so confident with basic grammar and that might prevent them from speaking Japanese more frequently, though they know advanced grammar.

If you would like to do a review of basic grammar (JLPT N5 and N4) by yourself, 「ひとりでできる 初級日本語文法の復習」is suitable . You can do a review of grammar that you have learned in class, and try good exercises. It might take just 2 months for you to be confident with grammar by this book.

This book is highly recommended for people who have passed JLPT N3 , N4, & N5 and would like to be more confident with grammar.

本を読んでいると、「〜と思うまもなく」や「まいか」など、普通の辞書には載っていない表現をよく見ます。
そんな時に、どうやってそのような表現を調べますか？
教科書や、ＪＬＰＴのノートを調べるのは時間がかかるし、それに載っていないこともあります。

そんなときは、そのような表現を調べるための辞書を使いましょう。
何冊かいいのがありますが、ＪＬＰＴ１以上の表現もすべて載っているのは「日本語文型辞典」(byくろしお出版)だけです。この本はとても調べやすく、また本当にたくさんの例文も載っています。
日本語の先生もこの本を使っている人が多いんですよ（秘密ですけど）
例文はどの本よりもたくさんあります。
しかし文法の説明の書き方が難しいので、説明よりも例文をたくさん読むためにこの辞書を使うのが、いい使い方です。
ただ、今はまだ「日本語版」「簡体字版」「繁体字版」しかありません（ベトナム語版や韓国語もありますが）
「英語版」は2014 年の10月頃に出版されます。

でも、日本語と英語はかなり違うので、特別な表現を勉強する時は、「日本語版」か「簡体字版」を使った方がいいかな。

紀伊國屋で売っていますよ。でもかなり高くて、たしか＄７０ぐらいだと思います。

http://nihongo.9640.jp/books/bunkei-jiten/books-bunkei.html

I believe people can learn most when they feel interested in what they will learn.

As everyone has their distinctive interests, I think we all have our own ways of learning. In class, I always try to do my best to conduct lessons which all of my students can find fun.

But as my students are very unique, I think they need self-study materials that are to their liking.

オタジャパ!  オタクな例文で覚える上級表現&文型 might be an ideal advanced level textbooks for those who like Japanese manga and anime. Example sentences should be unique and interesting to them.

Please note that this textbook is for advanced learners =)

Many advanced level learners say that "けいご" (keigo - honorific speech) is difficult. This is common because most Japanese language schools don't allocate enough time to teach けいご systematically. 

But if you would like to learn けいご by yourself, then 新・にほんご敬語トレーニング will be of a great help! You can understand in what kind of situation you need to use けいご, and the book gives you plenty of excise of 敬語.

You can buy (or order) the textbook in Kinokuniya.

http://www.amazon.co.jp/%E6%96%B0%E3%83%BB%E3%81%AB%E3%81%BB%E3%82%93%E3%81%94%E6%95%AC%E8%AA%9E%E3%83%88%E3%83%AC%E3%83%BC%E3%83%8B%E3%83%B3%E3%82%B0-%E9%87%91%E5%AD%90%E5%BA%83%E5%B9%B8/dp/4872178564