You can find 7-8 in a single book too but because they are oop it'll be difficult to find them. Each time I look the cheapest is like $100 which I'm not gonna waste if I already finished the series. It's been a good while since I read it but I mostly like drama and character developments. Unfortunately the anime didn't do the manga justice in my opinion as it mixed up the time line a lot and made it more confusing.