Insufficient for preparation — disappointing as a teaching tool
It is difficult to understand how a book like this has received such high ratings. Perhaps some readers lack the necessary background to perceive its shortcomings, or are unaware that the teaching approaches it follows are minimal, outdated, and in many places ineffective.
When it comes to writing educational material, whether for exam preparation or guiding beginner students, we cannot ignore the foundations of language teaching. Basic elements such as the order of writing ideograms (書き方), a rich set of exercises, essay writing, authentic texts, cultural references, and audio material are an integral part of any serious manual. It is precisely in these areas that this particular book is completely lacking.
The few exercises included are limited to simple sentence completions, without promoting active use of the language or meaningful understanding. Even the Kanji are presented without any reference to their correct writing or arrangement.
Personally, I cannot understand how such an inadequate aid can be considered sufficient for serious preparation. Its high rating creates false impressions and risks misleading those taking their first steps in learning the language.

This book, as mentioned in the preface, is an aid for anyone who wishes to learn the Japanese language (It briefly covers the grammar of level N5, it is not a learning book that can be used independently. That is why, in the preface, it is written that it is an aid). It starts with the learning of the hiragana and katakana scripts. From the second chapter onwards, it begins teaching Japanese grammar, which it presents in summary (it is also stated in the preface that the manual is a summary of Japanese grammar at level N5). Gradually, it also introduces you to kanji (the third script of the Japanese language). For their pronunciation, it uses furigana (which is an auxiliary reading tool for kanji, consisting of smaller kana written either above or next to the kanji to indicate their pronunciation). One of the negatives of the book is that it does not contain listening exercises, which is very important. Also, it does not teach you the order in which the syllables and logograms are written. But for this, you can, for example, use the following website which teaches you the order in which they are written as well as how they are pronounced (although the book does write how they are pronounced).
https://www.nhk.or.jp/lesson/en/letters/hiragana.html
At the end of the book, apart from the solutions to the exercises in the appendix, there is a collection of the Kanji that we need to know for level N5 as well as the words we saw in each chapter.
As a self-taught learner, I can say that this book is a good aid for learning the Japanese language. Everything is written simply and understandably. If someone wants a book that explains the grammar in more detail, I recommend buying the book 'Japanese Grammar with Exercises' by Katerina Lefa.

The unique book for learning Japanese in the Greek language.
It is necessary to emphasize that it is not for self-taught teaching but in accompaniment with a Japanese teacher.
It is an excellent supplement for easier learning in a tutoring center or private lessons. I highly recommend it.

The problem with this particular book is that it is not exactly what it claims to be. It states that it is a book for learning Japanese in Greek and that it includes material for the JLPT, but that's about it (and even that is poorly presented).
I went through this book just to find the countless mistakes it has (even in the answers, where things are not so good).
I do not recommend it to anyone, especially not to those who want to do independent study. It doesn't even have texts for reading practice. What kind of preparation does it offer for a certification?
The issue with kanji is also unacceptable. I won't say anything more. The stroke order and the rest are nowhere to be found.
Also, a very important detail: the font they have chosen is absolutely unacceptable, as in most of the kana characters that have "jumping" elements, they are nowhere to be found.
In short, no.
Happy reading.

Anyone who managed to learn Greek with the "modern Greek grammar" of primary school will be able to learn Japanese with this book. Beautiful book.