Is Secret Dōmei based on a book?

Common questions

Is Secret Dōmei based on a book?

Yes. Secret Dōmei is based on the book Secret Alliance.

Who wrote the book Secret Dōmei is based on?

The source is Secret Alliance.

Should I read the book before watching?

If you like knowing the full story and characters first, read Secret Alliance before you watch. Adaptations often change or cut plotlines, so the book is a different experience even if you've seen the TV series.