Since it is still an ongoing manga series there isn't a complete set of volumes, I think there are 15 with a new volume on the way or something like that. But new volumes are still getting released so there isn't a exact number yet ^^
Chapters so far: 86 (hope a new one comes out soon)
I'm pretty sure manga is the comix so in that case there are 15 books so far it least in America. Although if you go online or download manga reader as an app there are a lot more chapters ranging farther then book 15. I hope I answered your question.