If you are just beginning to learn the Japanese language, knowing the basic grammar rules will prove to be useful.
However, Japanese is not difficult. The biggest obstacle is probably the writing system and this book will help you narrow it down.
This book, written for the Japanese beginner student, explains the basics and how Hiragana, Katagana, Kanji, and Japanese grammar in general is used; it helps you to get an overview on how to start and proceed.
This book shows you the first steps and what you need to get started, it also makes suggestions of effective learning methods which are fun to do on a daily basis.
You also get a practical Japanese phrasebook suitable for travelers and students.