Harry Potter and Order of the Phoenix

I’ve been reading it for 6 weeks， but I haven’t finished it yet! I mean this book is from the library， so I have to finish it before going back to Japan… Well， I don’t know if it’s possible…I have no confidence of it.
Anyway， I’ve read only Harry Potter series as English versions. I mean since I started to read the first one， I’ve never read its Japanese versions.
But， I’ve never been able to finish reading them before the Japanese versions coming out.
So I hope I’ll be able to finish it by September.