Kakuzu Biology Speculations

Kakuzu Biology Speculations

Obviously it there is no realistic way to make sense of how the HELL Kakuzu’s body works, but it’s still fun to think about!

Okay so first of all, what does Earth Grudge Fear actually seem to do to his body? I’d say it’s safe to assume Kakuzu was a regular ass ninja before he used the kinjutsu, and that it was forbidden in the first place due to both the cost of live hearts and the danger posed to the caster. It seems as though all his internal organs and muscle was replaced by the strange threads, and I’d extend this to most, if not all, of his skeletal system alongside it. Personally, I see the Glasgow’s Smile and stitched-up limbs as signs of something forcing entry into his body and stretching it to the point of tearing, but this is probably just a design choice. He can move these threads at will, and can turn them into live creatures outside the body that act in his will. 

So, if his internal organs have been decimated by Earth Grudge Fear, how the hell is he alive? My favourite theory is that Earth Grudge Fear could actually be a type of summoning jutsu, where these thread creatures feed upon the internal organs, muscle and bones of the body before merging with the host and replacing the musculoskeletal and nervous systems - forming a mutualistic, parasitic relationship with the summoner. But what happens after? How does Kakuzu receive the energy needed in order to move, fight, speak and sustain perhaps up to five other living organisms on top of himself?

I believe this is where the hearts come into play. The caster will supply the creatures with a number of hearts that they will slowly feed upon over time, providing energy to the body, alongside elemental chakra and keeping Kakuzu ALIVE. If he has only one heart, then I think these five creatures could merge together into one to conserve energy and provide it to all of them equally, leaving them with only one type of chakra gained from said heart. If the creatures are outside the body and their own heart is lost, they will die however may be able to be manually merged with the others and resuscitate them.

Five hearts for six organisms isn’t a lot of energy, however - if this were to sustain them then they’d need to have freakishly slow metabolisms and waste as little energy as possible. This may be how Kakuzu is able to live for so long without aging: a slow metabolism! This is just speculation and can be attributed to personality, however to me Kakuzu doesn’t seem to move around very much. He stands still a lot of the time, not even moving an inch (for example, when Hidan was fighting Team 10 by himself) and I don’t believe we ever see him run outside of combat. In combat, too, his movements are very precise and hard-hitting, almost as if he’s trying to be as efficient as possible in order to conserve energy. Again, this can be boiled down to personality. It would make sense that he would move as little and as efficiently as possible outside of combat, and may require crazy amounts of sleep or even enter hibernation-like phases during certain times of the year, perhaps when business is slow or he could even receive something like medical leave. This means that during combat, it may be a life-or-death situation. He expends A LOT of precious energy during combat, and so he may actually be required to kill his foes in order to replenish his hearts and ‘eat’ so to speak. It would make sense if he also has some sort of deal with many bounty houses and use his canon subordinates to collect spares to keep in safehouses or be available for him to take as needed. It is shown that these bounty houses have huuuuge morgues, after all, so plenty of bodies. He may also use a large portion of his money to buy hearts off the black market, and this could be a further explanation for his greed!

Overall, I think Kakuzu’s Earth Grudge Fear jutsu results in a mutualistic parasitic relationship with the thread creatures and the caster’s body - the caster being able to control these creatures at will while providing energy to the creatures. This results in a very slow metabolism as they may eat the hearts he collects over time, which can be replenished through bounty houses, the black market, enemies and his subordinates. This explains his ruthless efficiency. I enjoy speculating these things, and Kakuzu is one of my favourite characters; he is very interesting and could’ve been explored SO MUCH more!

Idk who would read this but figured I’d put it here :P