yes thats tru but i just thought it was sad!!... like zabuza and haku... when they died it was so sad i cried... and now there forced to fight. i considered them good guys when they died. same as asuma the why he died was so sad! and when they came back it messed up there memory... ): thats all...
-chatte
Well, that was Kabuto's doing. They're personal feelings were at the beginning - Haku and Zabuza - and at the end - Asuma.
When first introduced in the Edo thing, Haku and Zabuza still remembered about what happened when they died and if you remember, Zabuza, before Kabuto erased his personality, asked him to kill him once again, in order for their will to stay the same as before they died.
And Asuma, when Chouji finally punched him he regained his personality after being erased, as well, by Kabuto and said that he is proud of him and told Ino Shika and Chouji that he has nothing to say to them as their Ino-Shika-Cho combination was perfect.
So their memory was still the same, only that Kabuto made them killing machines.