Originally Posted by Nejifan
healing the cells would not alleviate pain. regardless of his healing ability, he would still feel the same amount of pain as anyone else.
dude, if I cut you and your wound heals in 0.25 of a second you don't feel pain.
The body does not feel pain instantaneously it has to travel on nerve endings and reach your pain receptors.
If you heal yourself before you body realizes there is any damage you don't feel any pain.
Kabuto is just that good, but rasengan overpowered his ability to heal faster than he took damage, thats why there was a delayed reaction before he felt anything.