[omoikane]

If you are interested in that kind of books, there is also:

https://en.wikipedia.org/wiki/The_Complete_Manual_of_Suicide

This book used to be banned due to its contents, but in 2012 I was able to easily buy a copy from Amazon Japan. And now it's only sold in their third party marketplace, not sure if it's banned again.

[ehPReth]

For the curious, seems to be available here:

Original Japanese version with pictures/design/colour: https://www.mediafire.com/file/0eknpsoz6p87af8/完全自殺マニュアル+(鶴見...

English Machine/Human translated .txt file: https://www.mediafire.com/file/qb7b5ha20hyzl56/The+Complete+...