Sorry if this question seems redundant to some others, but I'm having a really hard time trying to figure this one out. I've been searching the internet on this for a while now and can't seem to get a clear answer.

So let me explain. I want to put a novel together, like a historical fiction of sorts, about the Japanese ninja. I've been reading English translations of some old ninja scrolls, namely the Bansenshukai. The Bansenshukai is considered like a "ninja manual." Anyway, for example, this book has things explained very clearly, like some of the spying tactics used, ways to predict weather, how to read people, and it even cites some prayers. If I decide to move forward with writing this novel, would it be legal for me to use and reference some of the things mentioned in this book? Should I reference and give credit to the Bansenshukai or whatever scroll I'm using for some of the activities shown in the book? As for the prayers, would it be OK for me to write them word for word within the book as long as I give proper credit, or should I just avoid it altogether?

I'm trying to make this novel interesting but as close to real history as possible. Again, it's totally fictional but I'm using real-world actions. I just don't know if something like, for example, chanting a prayer, or how to tell if it's going to rain today, is something that's necessarily copyrighted. But it's already been published in another book, so that makes me wonder if I should at least give credit.

Any insight is appreciated.

1 Answer 1


(The usual "I am not a lawyer" caveats apply)

The original Bansenshukai is from the 17th century, so all its contents is by now in the public domain. The same may not be true for the translation, however. According to wikipedia translations were made after WWII, so they will probably fall within author's life + 70 years.

As I understand it, that means that you cannot use excerpts of the translation without permission. So you would need to seek permission to reproduce the translated prayers, for example.

However, you should be able to use anything described in the book. Things like activities, and tactics, don't depend on the translation. They were already in the original, which is in the public domain.

Should you give credit? For parts that are copyrighted, you will probably need to (I imagine that would be a condition for use, when you get permission). But I'd also argue that you'd probably want to. Because giving credit tells your reader it's based on something real and historical.

  • Thanks so much, this helps me know where to start. I do have one other question though, I searched for the Bansenshukai in the Catalog of Copyright Entries. I couldn't find it when searching under name, publishing company or the author/translator. I feel I should still give credit as I would be referencing real history, but do I still need to get permission if this is the case? Mar 30, 2022 at 14:04
  • @StringCheese One thing to keep in mind is that copyright applies (in the US and many other countries) regardless of whether it is registered. If I read it correctly, however, registration is necessary before they can sue you in federal court (in the US), but it can be done after infraction. If you can find a website for the author or publishing company, that might be the easiest way to get in contact. I wouldn't honestly expect them to sue, but there's also not really a reason not to make a best-effort to ask permission.
    – user54131
    Mar 30, 2022 at 15:21

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