Re: Tsunade stated that she can't die in a fight
And while I don't hold the belief that Tsunade would survive decapitation, I find it foolhardy to try to defy both the manga and databooks using logic that applies to the real world only. We cannot state the laws of the narutoverse, as last I checked medical ninjutsu was not possible, nor is the splitting and dividing of slugs, nor can snakes, dogs, slugs, toads, etc. speak Japanese.
What you guys are arguing is how Tsunade would fair if she was a person in our reality. But then consider this, if Tsunade was operating under the laws of this reality that would mean every time she hits any object the same amount of force is applied back to her. Though I suppose that's not too far of a stretch considering if one were to travel at the speed of light in the real world the would literally be ripped to shreds, in the same fashion as Jinton. One could argue you would be broken down to smaller than a molecular level. Which is something that Kishi acknowledged yet Tsunade made it with relatively few cuts on her whole body, so far as I know within this laws of this universe the only thing that can move at the speed of light without being destroyed are photons. Furthermore, the moment she made contact with Madara both she and A and Madara and Muu should have all gone splat based on the momentum and mass.
And after the sannin fight when Gamabunta's sword disappeared according to the laws of our universe she should have been immediately killed when she made contact with the ground.
And when her intercostal muscles were cut by Kabuto she should not have been able to breathe let alone run. And when she punched Kabuto, the force traveled through his body splitting the earth underneath him, according to our laws the majority of the bones in his body, especially the skull should have shattered and he should have died instantly. With Tsunade's bicep muscles cut she should not have been able to punch. With Tsunade's abdominal muscles cut she should not have been able to counter or run.
And while the heart of a human is not perfectly center, a portion of it is therefore, Orochimaru's sword should have went directly through her heart killing her instantly. His sword would have pierced the lungs on the third strike, and would have slashed lungs and heart on the second.
Also based on the height at which Tsunade has jumped holding Gamabunta's sword she will have superhuman strength in her legs which in turn would allow her to run much quicker than a human of lesser strength.
Also people have been saying that Tsunade cannot regrow what she does not have, as per cell division only applies to what is there, but that would then force the question of how she regrew her small and large intestines, pancreas, stomach, liver, kidneys, and gall bladder. When the initial Susanoo sword that stabbed her would have destroyed those completely. Which leads me to the point that under our laws Tsunade should not have been able to break that susanoo sword because of the conditions of her spine and likely punctured lungs, much less swing it. Nor should she have been able to withstand being slammed into the rocks as hard as she was, unless as mentioned earlier her durability is so great that she can withstand a force that would ordinarily rip someone to pieces near the mass of photons. Additionally when she was penetrated by two susanoo swords she would have been missing half of both of her lungs, in fact the only organ in the region that would not have been destroyed then and there is the heart.
My point being that you cannot apply real world logic to Naruto and have it refute direct statements made by cannon sources. The manga being the most acceptable source of information and the databook being the second most acceptable. Both the of them say Tsunade can not be killed in battle until her chakra runs out. With Tsunade's yin seal she has a very large amount of chakra stored in her forehead, another chakra system also appears to be the stomach in the narutoverse. The only way you can really argue on the matter is using contradictions within the cannon sources and then you build upon those contradictions using logical processes.