I got this book at the Family Mart near my house. It’s a book all about Ninja. Yes it’s all in Japanese, but it has a wealth of pictures and illustrations, so I can still understand it a bit.
I contains information on Ninja techniques.
And useful information, like how to tie a Ninja mask.
It also has a lengthy section on Ninja history, and a map of Japan showing all of the Ninja clans for the different areas. Maybe someday I’ll be able to read through it when I learn more Japanese.