|English anime||Life Energy|
|Appears in||Anime, Manga|
Life Force (生命力, "Inochiryoku") is the life energy of all people and living things based on the strength of their physical energy. It governs one's stamina, durability and longevity. It does not carry memories or experiences and for the most part cannot be controlled. It can be further defined as a persons physical energy's potential to sustain and invigorate them.
One's life force determines their lifespan and overall vitality. The more one has, the longer they live and the slower they age. Life force is ordinarily not visible to the unaided eye unless it is highly concentrated or manifested in large amounts. This is extremely rare. If a person has a muscular life force their chakra becomes more potent and their ability to withstand exhaustion and powerful attacks without succumbing increase. Having a large life force acts upon different people in different ways. Injuries that are generally fatal may still kill but do not as quickly一it is possible to lose a limb or even be bisected and still survive or even function normally. Those with these traits are strong enough to survive the removal of tailed beasts, although they are still left severely weakened afterwards and will inevitably die.
Physical Energy and Yang Release
One's life force power direction depends upon the quality of their physical energy. Physical energy is energy produced by all of the body's cells and is one of the components to chakra, the other being spiritual energy. As such, it is possible to increase the power of one's life force, though the amount generally seems to be inconsequential.
Yang Release (which is chakra with a higher ratio of physical energy than spiritual energy) is said to "govern vitality, granting life to forms that have none." Naturally then, the greater one's physical energy the greater their life force and the greater their life force the greater their Yang Release.
Because life force is based on physical energy it can also be used to restore physical damage. Medical Ninjutsu can be either Yin Release or Yang Release. Life force healing is generally natural and has often been called Regeneration Ability. This power, however, cannot restore limbs unless one possesses a life force on par with that of the Jūbi who allowed Madara Uchiha to regenerated a tragically deformed body. Madara did this, however, because he possessed both the Yang and Yin power of the Sage of Six Paths. The Nine Tails Fox yang portion allowed Naruto Uzumaki to heal from damage at a much quicker rate. Regularly, however, those with life force healing simply heal from damage quicker than others. This is the case with all shinobi who possess a greater physical energy than average people.
Apparently, if a person's soul has not passed on to the Pure Land they can be bought back to life using certain Reincarnation Ninjutsu like Chiyo's One's Own Life Reincarnation which uses chakra as a medium to transfer one's life force to someone else. Even if someone is not dead the life force can still be given resulting in their recuperation but the weakened state of the technique user. The exhausted state of the user in such a situated further illustrates life force's connection to physical energy.
Life Force in Use
In all these cases, life force is always linked to physical energy and Yang Release, demonstrated in energetic and life-giving abilities. It should be noted that the Senju and the Uzumaki clan (descendants of the Senju) are praised as having the greatest life forces.
- Hashirama Senju, the lord of the Senju, no doubt inherited his clan's life energy in a particular way, giving him the ability to produce life with his chakra in the form of Wood Release. In order to create plant life, one would certainly need vitality and life energy to do so. His granddaughter, although not inheriting this ability, did indeed inherit a powerful life force from him.
- Mito Uzumaki married Hashirama Senju and was born far before Kushina Uzumaki. She lived well pass 100 years old and even retained the color of her hair in her old age. She is the grandmother of Tsunade.
- Tsunade's display of nature superhuman strength, a clear sign that she has a powerful physical energy. Tsunade is a descendant of both the Senju and Uzumaki, inheriting both their vitality. Tsunade also possesses enough life force to cling to life, even after being cut in half or losing most of her chakra.
When Tsunade was cut in half and her body exhausted, her life energy waned and she became much weaker, albeit still surviving.
- Naruto had the Yang portion of Kurama sealed inside of him. When coming into contact with Hashirama's clones (the Zetsu) these clones were overcome with life energy and bloomed into trees.
- Karin Uzumaki uses her life force to heal even those on the brink of death through the biting and sucking of her flesh. This would be characterized as Yang Release medical ninjutsu.
- Kushina Uzumaki had the Nine Tails Fox extracted from her and lived for many moments afterward, even capable of moving quickly to shield her newborn son. This is a testament to her physical energy and capacity to continue forward when she should be dead.
- The anime and manga never truly expanded on life force. Based on deduction and a bit of research, this is the conclusion on life force's definition that is canon.
- The Uzumaki clan is known for their strong life force which gives them their famous power.