Kakuzu’s Earth Grudge Fear

Earth Grudge Fear is the once prized forbidden jutsu of the Hidden Waterfall until it was stolen by the missing-nin Kakuzu.

It was invented by a medic-nin who specialized in using threads infused with medical chakra to stitch up wounds, a primitive style of treatment that went unrecognized by the wider world. This ninja would go on to develop a powerful and versatile ninjutsu that drastically modifies the human body, granting the user the ability to generate organic black tentacles from their own flesh and chakra. The tentacles can be produced in great numbers and length, and manipulated as easily and precisely as the user’s own limbs.

The primary purpose of the tentacles is for sewing up any injuries the user or others might suffer, commonly by reattaching body parts. The tentacles are infused with a special kind of medical chakra that instantly reconnects any kind of severed tissue, including nerves and chakra pathways – as a result, a reattached limb is immediately restored to full functionality. The tentacles can also be used to transplant organs and limbs between different people without any risk of rejection. A patient can even be saved from decapitation if the head is reattached before brain death sets it.

Furthermore, because the tentacles do not require hand-seals to generate or control them, the user of this kinjutsu is granted an incredible power of recovery from physical trauma – they can literally will their body to pull itself back together from any injury that is not instantaneously fatal.

However, while the medical usage of this kinjutsu is almost miraculously effective and versatile, it is also much cruder than other advanced medical ninjutsu such as the Mystical Palm Technique. The healed tissue is not bonded very strongly and it is very easy to accidentally reopen the wounds through physical exertion. It is thus necessary for the tentacles to remain in the body to act as sutures, holding the tissues together until it can heal properly over time or further medical ninjutsu can be applied.

For this reason, any ninja who uses this kinjutsu and frequently engages in battle will eventually come to have a body that resembles a rag doll – the more injuries they’ve accumulated over their lifetime, the more stitches are required to keep their body from falling apart.

The secondary purpose of the tentacles is to be used as weapons. The tentacles can be extended very quickly and accurately in order to ensnare and impale opponents. The user can also generate a large amount of tentacles and compact them together around their body into thick tentacles for long-ranged combat.

Kakuzu, once an honourable samurai and then a proud shinobi of the Hidden Waterfall, was the first to be able to perform the kinjutsu after its creator. The injuries inflicted upon him in his life of warfare led to the discovery he could use this technique’s ability to transplant organs to steal the heart of another human being and assimilate it with his tentacles, allowing him to connect his chakra system to the chakra generated by the heart.

The heart retains the strongest chakra nature of the original owner – and a significant portion of their chakra – which Kakuzu could use as a shortcut for generating elemental chakra by channelling his chakra through their heart. This discovery led into another when he decided to steal the hearts of more of his enemies and learned that he could stock up to five hearts, ideally one for each element. Thus Kakuzu could cast any ninjutsu of the five nature transformations that he possessed knowledge of.

The vestiges of Kakuzu’s honour would lead to him mutilate himself in compensation for whenever he carved out the heart of an enemy, adding to his horrifically scarred appearance.

These abilities made him a very dangerous individual and the most prized fighter in his village. That’s the reason he was chosen to eliminate the First Hokage. It was believed that not only would he have the greatest chance of the defeating the man, but that by stealing his heart he would give his village a potent tool for controlling the Tailed Beasts.

Kakuzu only survived that battle by faking his own death. His stolen hearts are able to sustain his life force and slow his aging process so that, as long as he still has a single beating heart, he can stay alive with a quasi-immortality. His skill with Earth Grudge Fear had led to a derivative that enables his stolen hearts to split off from his main body with masses of tentacles and act independently for a limited time. He took advantage of that independence to fool Hashirama with his lifeless body until the danger had passed and the heart returned.

After he was punished by his village for his failures, he stole the scroll containing the kinjutsu to prevent others from gaining his power and restored his strength by carving out the hearts of the village elders before abandoning his home.

In his following years as a bounty hunter, Kakuzu’s skill with Earth Grudge Fear only grew. He learned of a way to give his hearts even greater independence by incorporating them with chakra transmitting masks, giving them a higher level of sentience and monstrous bodies designed for battle. They can each release their chakra nature in a destructive form and Kakuzu can use them to channel his elemental ninjutsu through the hearts remotely.

The final stage of his terrifying advancement of Earth Grudge Fear was when he developed a method to permanently convert his own body cells into those tentacles. His tentacles can perfectly simulate most of the functioning of any other cell, even including the neurons of the brain, turning him into a mass of prehensile tentacles wearing human skin.

This rendered his body virtually indestructible and ageless. The only weakness of his new form was that the tentacles couldn’t generate chakra, so he was forced to retain his vulnerable untransformed hearts to fulfil that essential function.

Co-written with Altered Nova