Tōtōsai

was an elderly swordsmith yōkai specializing in the demonic, who forged Tessaiga and Tenseiga from the fangs of his old friend, the Inu no Taishō. He spent most of his time at his forge inside a volcano, but sometimes traveled elsewhere on his flying three-eyed ox demon named Mō-Mō.

History
Tōtōsai created Tessaiga at the Inu no Taishō's request, granting the blade the power to steal abilities from those it fell. When the Inu no Taishō defeated Shishinki and gained the deadly Meidō Zangetsuha technique, again at his request, Tōtōsai separated the technique into a blade made from a part of Tessaiga. This new blade could bring back a dead person once and send all the undead back to the afterlife. Tōtōsai considered calling this new weapon the "Coffin Cheater", but the Inu no Taishō preferred to call the blade "Tenseiga". After the Inu no Taishō's death, the Tessaiga was bequeathed to his youngest son Inuyasha, and the Tenseiga to his elder son Sesshōmaru.

Tōtōsai also learned that the Inu no Taishō believed Sesshōmaru would eventually come to manifest his own weapon, the Bakusaiga, when he became worthy.

Tenseiga and Tessaiga
Tōtōsai was commissioned by Sesshōmaru to create a sword that rivaled Tessaiga; however, he instead fled with Myōga, who informed him Inuyasha had successfully used the Kaze no Kizu only once. Believing that Inuyasha could protect him from Sesshōmaru, Tōtōsai met with him, testing Tessaiga to see what had become of it. To his sorrow, he found the blade was full of nicks and wondered if Inuyasha had been using it to chop down trees. After revealing his identity, Sesshōmaru arrived in pursuit of Tōtōsai. He had the brothers fight briefly before creating a ring of fire to allow him and Inuyasha's group to escape. After sharpening Tessaiga for Inuyasha, Tōtōsai prepared to return home; however, Sesshōmaru returned, this time using a dragon's claw as a replacement arm that was able to hold the Tessaiga. Tōtōsai watched in amazement as Inuyasha invoked the Kaze no Kizu willingly against his brother; however, Tenseiga protected Sesshōmaru from the attack. Returning home, Tōtōsai realized "that cunning old hound" had him forge the Tenseiga so that fighting for the control of Tessaiga would be pointless.

Inuyasha later brought the broken Tessaiga to Tōtōsai for repairs. Tōtōsai used one of Inuyasha's fangs as a bridge to bond the pieces back together. After three days, Tōtōsai set out to give Tessaiga back to Inuyasha. On the way, he came across his former apprentice Kaijinbō, who was possessed by the evil blade Tōkijin, created from the fangs of Goshinki, the demon whose fangs broke Tessaiga in the first place. When Kaijinbō was destroyed by Tōkijin's evil, Tōtōsai explained to Inuyasha that Tessaiga had become heavier because the fang he used to repair it was Inuyasha's, and that Inuyasha had not yet achieved the level of strength his father had possessed. When Sesshōmaru came to claim Tōkijin, Tōtōsai provided another distraction by creating a wall of fire.

After Inuyasha had gone through numerous transformation due to his demon blood, he visited Tōtōsai, fearing for Kagome's safety if he were to lose control again. Tōtōsai saw that his human heart was suffering from this, so he sent Inuyasha to the Valley of Ryūkotsusei to slay the demon that his father was unable to. Tōtōsai later met the rest of Inuyasha's group and explained the task he sent Inuyasha to do. However, when Ryūkotsusei was awoken by Naraku breaking the seal put on him by the Inu no Taishō many years before, Tōtōsai blamed Inuyasha. He and the others watched in amazement as Inuyasha fought against his demon blood and successfully used the Bakuryūha for the first time to kill Ryūkotsusei. Tōtōsai was even more amazed to learn Inuyasha thought the Ultimate Technique of Tessaiga was a new trick he had put in it.

Lending Assistance
Inuyasha later came to Tōtōsai, seeking a way to break Naraku's barrier. However, Tōtōsai accidentally tricked him into preparing a bath for him under the guise of "training". Myōga later told him that Inuyasha would most likely kill him for his trickery. Revealing the ruse, Tōtōsai was whacked on the head; however, as a reward for the hard work, Tōtōsai asked Myōga to tell Inuyasha that killing the barrier guardian of the bat demons would grant Tessaiga the power to break barriers.

After Sesshōmaru broke Tōkijin in battle with Mōryōmaru, Tōtōsai was summoned by Tenseiga. Noticing that the Tōkijin was no more, Tōtōsai demanded Tenseiga back. He said that since Sesshōmaru's heart now had what it was lacking before, it was time to reforge Tenseiga into a weapon by endowing it with the Meidō Zangetsuha. Revealing the technique's use, Tōtōsai left Sesshōmaru to perfect the Path to the Underworld it created.

Inuyasha later came to Tōtōsai, asking about a blade called Dakki. Tōtōsai warned Inuyasha that losing to the true blade (as the broken one that Inuyasha was having him examine was a fake) would reduce Tessaiga to a useless rusty blade, most likely unable to suppress the demon blood in him any longer. When Inuyasha succeeded in destroying the true Dakki and gaining its power to steal demonic energy, he sought out Tōtōsai again; he revealed Tessaiga heated up when drawing in demonic energy to warn Inuyasha to let go of it before a backlash of energy could kill him. Tōtōsai sent Inuyasha to train with the Yōreitaisei to learn how to detect demon vortices.

Knowing Sesshōmaru would eventually find out the truth about Tenseiga and the Meidō Zangetsuha, Tōtōsai prepared to move to escape his impending wrath, only to find Sesshōmaru sending part of his home to the Underworld with a Meidō. Tōtōsai revealed that he indeed created Tenseiga to house the Meidō Zangetsuha. He was then surprised to learn that Sesshōmaru had realized that Tessaiga could reabsorb its lost technique now that it had been mastered. Creating a ring of fire to block Sesshōmaru from sending a Meidō at him, Tōtōsai told Sesshōmaru that since his thoughts were clouded, he could not learn what the Inu no Taishō's long-term plan was. Tōtōsai then barely avoided the Meidō that swallowed most of his home.

When Tenseiga and Tessaiga clashed, Tōtōsai appeared before Inuyasha's group, Jaken, and Rin, using Mō-Mō as a movie projector to show them the battle between the blades. Tōtōsai was amazed that Inuyasha was able to realize Tessaiga's will so quickly; however, he bluntly proclaimed that there was no way for Inuyasha and Sesshōmaru to escape the Path to the Underworld. However, he was proven wrong when Tenseiga (which had been broken on Tessaiga, but repaired itself) guided Inuyasha into using the Meidō to lead him and Sesshōmaru back to the World of the Living.

Tōtōsai later sensed that Bakusaiga would soon appear and took off, arriving at the battle between Sesshōmaru and Magatsuhi. He watched as Bakusaiga appeared alongside Sesshōmaru along with a new left arm. He explained the Inu no Taishō's belief and why Bakusaiga hadn't appeared until then. He later created a sheath for the deadly blade, and explained to Inuyasha that Magatsuhi could only be cut down by Tenseiga.

During the final battle inside Naraku's body, Tōtōsai watched on with Myōga, explaining that the Meidō Zangetsuha would soon evolve to match Inuyasha's fighting style. It soon did, turning into blades that severed objects just like a blade would and sucking them into the afterlife.

Later life
Tōtōsai remained at his volcanic home, allowing Myōga to stay with him. Flying on Mō-Mō, Tōtōsai met up with Kohaku, riding on Kirara, to give him a new kusarigama-like weapon, saying "it's a bit heavy." Before parting ways, Tōtōsai asked Kohaku if he ever visited Sango from time to time, only to hear that the young demon slayer found it too crowded at her house.

Physical description
Tōtōsai took the appearance of a scranky old man. He had huge eyes with pinpoint pupils that were always seen wide open (unless expressing emotions). Balding, Tōtōsai had what remained of his hair tied in a topknot. He had a thin goatee at the end of his chin that was always scorched, as well as a mustache that was (seemingly) shaved in the middle. He wore a green hoari with black horizontal strikes on it, with matching hakama. Like Rin and Inuyasha, Tōtōsai went barefoot.

Personality
Tōtōsai could be described as eccentric, insane, or senile. At some times, Tōtōsai acted like he was suffering from Alzheimer's, by claiming that he did not remember things that happened recently to avoid being punished. He loved to poke fun at others, even with Inuyasha, although he usually ended up with a whack to the head in this case. Tōtōsai was protective of the blades he forged, even wanting to end Tessaiga's suffering at Inuyasha's hands by melting it into cutlery (during his first meeting with Inuyasha). He could not stand crafting blades through or for evil means, banishing his apprentice Kaijinbō for killing ten innocent children to forge a demonic sword. He was greatly concerned for his life, knowing that Sesshōmaru and other demons would kill him if he didn't comply with their demands.

Powers & Abilities

 * Master Swordsmith: Tōtōsai created numerous blades in his time, being able to craft them with any ability that was within his power to grant. He could lock/unlock powers in the blades, such as with Tenseiga and the Meidō Zangetsuha. Tōtōsai also could repair other weapons than swords, such as Miroku's staff  and Hiraikotsu (after Kaijinbō cut it in half).
 * Communication with Swords: Tōtōsai could hear the "voices" of blades; for example, he said Tessaiga was singing a sad song because of how Inuyasha originally wielded it. He could also be summoned by them, such as when Tenseiga summoned him to Sesshōmaru due a change in the daiyōkai's heart. When Bakusaiga was about to appear, Tōtōsai heard numerous pieces of metal in his workshop vibrating, hinting either he could communicate with blades he knew about or could sense changes in the wielders of his blades.
 * Pyrokinesis: Tōtōsai was able to breathe fire to help him with forging blades, as well as make it erupt from the ground with a strike of his hammer. Not very powerful as an attack, this ability acted more as a defensive/escape-enabling strategy, although it did prove useful with dealing with the living dead.

Relationships
An old friend of the Inu no Taishō, Tōtōsai turned one of the fangs belonging to his friend into the mighty Tessaiga at his request. After the blade gained the power of the Meidō Zangetsuha from Shishinki, Tōtōsai complied with the Inu no Taishō's desire to separate and seal the technique into a new blade born of Tessaiga, the Tenseiga. When the Inu no Taishō died, Tōtōsai mourned his death along with Myōga and Saya.
 * Inu no Taishō

Tōtōsai was also an old friend of Myōga. He often teased Myōga about running away from danger, but allowed him to stay with him when he was not away looking for Inuyasha. Myōga also sometimes served as Tōtōsai's messenger, relaying to Inuyasha the tasks he needed to accomplish to master the new powers Tessaiga gained.
 * Myōga

Tōtōsai would often meet with Inuyasha when he experienced a problem with Tessaiga. However, he greatly disliked how Inuyasha originally treated the blade like a wooden club, badly nicking it. At first, he had a great lack of confidence in the hanyō's ability to understand the will of Tessaiga, but nonetheless assisted when he deemed it necessary. Tōtōsai often had to explain a great deal about Tessaiga and what tasks Inuyasha needed to complete in order to master its new abilities. Lacking any fear of Inuyasha, Tōtōsai often made wise-cracks that resulted in a whack to the head from the hanyō in response.
 * Inuyasha

Unlike Inuyasha, Sesshōmaru caused Tōtōsai great fear, forcing him to go on the run when he was asked to make a sword that rivaled Tessaiga. However, he reforged Tenseiga for the daiyōkai, unlocking the Meidō Zangetsua, due to the change in Sesshōmaru's heart. Also, knowing the existence of Bakusaiga, Tōtōsai did his best to help Sesshōmaru overcome the blade's test of worthiness, and made it a matching sheath.
 * Sesshōmaru

Known creations

 * Tessaiga
 * Tenseiga
 * Tessaiga's sheath
 * A sheath for the Bakusaiga
 * An kusarigama-like weapon for Kohaku

Trivia

 * Despite his reputation of being a powerful swordsmith and possessing a large knowledge of demon swords, Tōtōsai never wielded a sword for battle throughout the entire series.
 * Both his Japanese and English voices actors voiced Harumaki from Rumiko Takahashi's previous work .