Don't know. And I won't buy the fourth one untill the fifth one has come out anyway. When I read one volume I have to read the next one right away for some reason O.o But then again, I'll have to wait two months for the next one >D
But the main reason why I buy them in pairs is that the only day my mom can give me a lift is on Saturday when I have my piano lesson and then I'll have to wait 45 minutes out in the cold ;_; But when it gets warmer and I can go out with my bicycle again I'll probaly buy Inuyasha more often =D