Tenseiga

The Tenseiga (天生牙) is a fantasy sword from the anime and manga series InuYasha.

History
The Tenseiga is wielded by Sesshomaru, who inherited the sword from his father upon his death. The swordsmith Totosai created it along with the Tessaiga from the fangs of Sesshomaru's father, who was a daiyoukai (lit. great youkai) dog demon famous throughout the lands. Totosai claims that only someone who has the heart to cherish others would be able to use it, but confesses that he has actually little clue to the sword's mysterious powers. Sesshomaru, surprisingly, is able to use Tenseiga's abilities. According to Totosai, Tenseiga has chosen Sesshomaru as its master, regardless of whether he had a kind and caring heart.

Sesshomaru despises the Tenseiga for its lack of destructive power and early in the story, would attempt to acquire Inuyasha's Tessaiga using whatever means he deemed appropriate. Tenseiga has been used sparingly, mostly only when Sesshomaru feels like using its power for his own gains such as reviving the head of the yōkai Goshinki so that his fangs can be used to create the sword Tokijin; or when the sword compels Sesshomaru to use him for a good cause. One such example was the sword pulsing to tell Sesshomaru to revive Kanta's father, and in so doing, Sesshomaru learns the demon graveyard his father resides in figures into Naraku's plans.

Sesshomaru's human companion, a human girl named Rin, is brought back to life with the Tenseiga after she was killed by the demon wolves of Kōga; Jaken, Sesshomaru's assistant, is also revived by Tenseiga as well after Kaijinbo kills him while under the corruption of the Tokijin.

Abilities
The Tenseiga is sword which can bring the dead back to life by allowing a powerful user to see the pall bearer demons that take away the souls of the dead. As Tenseiga has the power to connect to the underworld, these demons can be cut and destroyed by it, allowing the soul to return to the dead's body. As the dead revives, their mortal wounds are healed. It is important to note that Tenseiga cannot really heal the living; it resurrects the dead. The literal translation of the kanji is "heavenly life fang" or "fang born out of heaven", but these are not necessarily accurate representations of the name's actual meaning.

Tenseiga allows its user to see and slay the beings from the underworld, as well as bringing up to 100 beings back to life in one swing. It is later reforged into a weapon capable of killing an opponent in a single blow along with its afformentioned powers of revival.

Since Tenseiga can harm the beings of the netherworld, the guardians at the gate that separates the Living World and the Dead, Gozu and Mezu, will not attack anyone who wields the Tenseiga for fear of their own safety, thus allowing them to pass the gate unobstructed.

Other than the power to resurrect the dead, Tenseiga has also the ability to protect its user by erecting a barrier in extreme cases or life-threatening situations. When Inuyasha unleashed the Wind Scar properly for the first time on Sesshomaru, Tenseiga, sensing that the blow was fatal, gave off a blue light surrounding him and teleported him to safety. This seems to be a built-in defense mechanism. Tenseiga has also protected Sesshomaru in several other dangerous situations.

Inheritence
It is possible that Inu no Taisho intended that Sesshomaru and Inuyasha inherit Tenseiga and Tessaiga respectively so that they could not kill each other. Likely knowing that Sesshomaru despised Inuyasha for being a hanyou and that Inuyasha would have a dangerous life, Inu no Taisho gifted Inuyasha with the powerful, destructive Tessaiga to protect himself and his loved ones and defend himself against Sesshomaru. Additionally Tessaiga seals Inuyasha's full demon blood.

Sesshomaru was given the Tenseiga, such that Tenseiga could never be used to kill Inuyasha and can protect him from Tessaiga's attacks. This could be planned by Inu no Taisho to instill brotherly kinship or at least respect among the two brothers. Both swords are compared by Totosai as two sides of a coin. Neither is superior or inferior to the other. Each cancels out each another as Tenseiga can save 100 lives with one strike while Tessaiga can cut down 100 beings with one strike.

New Abilities
Totosai later reforges the Tenseiga after Tokijin is broken because the Tenseiga had detected a change in Sesshomaru's heart where he felt feelings of fury and sadness for Kagura, prompting it to call out for Totosai and reforge it as a weapon as Sesshomaru had finally felt compassion for others.

The sword gains the Meidou Zangetsu Ha, which allows it to send enemies directly to the land of the dead as well as its previous resurrection power. Tenseiga allows its user to cut open the path or boundary that separates the worlds of the living and the dead. A dark arc is formed in which it "cuts" the enemy in a sense and sends it to the after life. Sesshomaru performed this attack successfully on his first try which surprised Totosai. In the beginning, the fissure was only crescent moon shaped. As Sesshomaru perfects the technique the arc will become closer to a circle which will be able to send the entire body of the enemy to the next world or hell. Thus, Sesshomaru finally accepts its potential as a weapon.

Sesshomaru has used this technique numerous times and seeks to improve himself by entering a mountain and training by killing demons living there. Later, he kills the Numawatari (demonic lake), which InuYasha and his companions could not defeat, with a single blow. He is closer to mastering it in chapter 470, when he purified many dead bodies, widening the opening.

In Ch.470, it was revealed by Sesshomaru's mother that a person cannot be revived by Tenseiga more than once. He realizes this when Rin, already dead, is not responding to Tenseiga and vice versa. However, at the end of Ch.471, Sesshomaru's mother apparently revives Rin using the Meidouseki, after leaving the Land of the dead.

Recently, Sesshomaru and his party encountered the mysterious Shishinki, a youkai with half a face that claimed to have fought Inu no Taisho in the past. It would be revealed that the ability Meidou Zangetsu Ha was originally his own, and that Inu no Taisho stole it from him with Tessaiga. However, the ability was deemed too dangerous to be retained due to it's nature, and Tenseiga was created out of Tessaiga to bear that ability. Shishinki demonstrated his mastery over "his" ability, by firing off not just a perfectly-circular Meidou (although far smaller than Sesshomaru's version), but also several Meidous at once (at present, Sesshomaru can fire only one at a time). Although the "incomplete" nature of Tenseiga is seemingly preventing Sesshomaru from mastering the ability, it would be show that when Tenseiga is in close proximity to Tessaiga, it causes both swords to resonate and allows former sword to create a perfectly-circular Meidou that is bigger and stronger than even Shishinki's version, as was shown when it absorbs Shishinki and his wave of smaller Meidous.

Swords of an Honourable Ruler
Tenseiga plays a major role in the 3rd movie, along with InuYasha's sword Tessaiga and their father's sword So'unga. When Saya, the spirit of the sheath, is no longer able to seal the demonic So'unga after 700 years (even though Myoga berates him for sealing the sword for only 200 years), the So'unga is freed and goes on a rampage to destroy all of humanity.

InuYasha and Sesshomaru are forced to reluctantly work together since So'unga is only weakened by the two fangs themselves. They eventually defeat their father's sword by combining InuYasha's Bakuryūha and Sesshomaru's Soryūha (which is strangely performed by Tenseiga instead of Tokijin).

It was also observed in the 3rd Movie that Tenseiga has the ability to cut and damage the undead. Tenseiga's life giving powers deal divine damage to the undead, causing far more damage than conventional attacks. This happened another time in the anime to defeat the lord of the Panther devas, but is never seen in the manga.

Tenseiga