If you're just starting deco like I have then you need a really good book to take you step by step to make simple sweets. When I first started there wasn't as many sweet deco tutorials as there are now so I had to buy Japanese books on making them to really learn the basics, as well learn from doing it on my own. The thing about buying sweets deco den books or any craft book that's in Japanese is if they will have "step by step" pictures. Those pictures are essential so you will know how to make your project with ease rather then struggling what to do next. I brought both books that had great step by step pictures and ones that was lacking and I had to figure everything out. Though if you don't want to go down that route there are enough polymer clay tutorials to fill in the basics these days. None the less I think its a good investment because you can get tons of ideas from the pictures inside the books!
The books I recommend are from
Pastel Sweets, I have two of them and been the most helpful and most easy to understand. They have clear and easy to understand pictures of each process. Best of all they go around 10 dollars each! The book itself is short and small but have enough information to keep you entertained but wanting more. The ones I have brought came from esty but going back to look for them I couldn't find any, BUT I have discovered something even more exciting! The Japanese site Rakuten that is home to many sweet deco stores is now in English and ships to the US! Even better I found 2 of the books from Pastel Sweets there and for a cheaper price. In fact I'm going to buy the last one in the collection sometime soon since I was looking for it. The seller also have tons and tons of deco supplies and per-made deco accessories to buy.
Rakuten shop
The seller's shop The pastel sweets book 1
The pastel sweets book 2 I hope this helps anyone that have been wondering about what sweets deco book to buy.