Dakki

is a yōkai sword that absorbs demonic energy. It was from absorbing Dakki's technique that the Dragon-Scaled Tessaiga was created. This sword has been used by Tōshū and Mujina (the latter only was in possession a prototype).

History
It was created by a sword-smith named Tōshū, who wanted to create the strongest blade around. Through experimentation and creation of many blades, he found that blades of stronger yin yield better results.

He started to collect broken swords from areas of conflict and despair. These acts soon earned the attention of the demon Ryūjin, who was drawn to Tōshū's yin and thus commissioned him (by Tōshū's request) to create Dakki.

In the manga and the anime, Inuyasha's group came to know about it after a badger yōkai, named Mujina, who tricked Shippō into helping him, fought with Inuyasha to steal the demonic energy with Dakki.

However this version was not the true version, as it easily broke from a simple knock of Inuyasha's sword. They took a piece of the broken blade to Tōtōsai, who examined it and told them about the sword-smith who forged it. When Inuyasha decided to find Dakki in order to upgrade Tessaiga, Tōtōsai warned him not to be overconfident, as even the fake version was able to steal demonic energy quite easily; should Inuyasha have to battle the true Dakki, he risked having Tessiaga devoid of its demonic energy and be in its battered form forever.

Later they rescued Tōshū from Ryūjin, who was angered that Tōshū had not yet completed crafting "Dakki". When Ryūjin was defeated by Inuyasha with his Backlash Wave, Tōshū used the sword to absorb Ryūjin's power, thus completing Dakki and gaining the Dragon Scales (in the manga, Dakki already has the dragon scales, and merely gained Ryūjin's demon power), then battled Inuyasha and began to steal the demonic energy from Tessaiga.

Through the course of the fight, Tessaiga began to crack as a result of having its energy stolen, while Tōshū began to turn into a yōkai himself. Soon Tessaiga turned back into its battered form due to the massive loss of energy, but not without finally making a small crack on Dakki. Despite the overwhelming sword skills of Tōshū under the influence of Dakki, Inuyasha still battles him alone, as he believed it to be a fight between Dakki and Tessaiga, and he did not want to waste the opportunity provided by it to destroy Dakki.

Eventually Dakki, sensing the danger of getting destroyed, used the demonic energy taken from Tessaiga to kill Tōshū, leaving behind only his hand attached to the hilt. Shortly after, the blade broke from the crack, releasing all the stolen energy which returned to Tessaiga, followed by the ability to absorb demonic energy.

Physical description
It takes the form of a large katana which, after Tōshū killed Ryūjin and absorbing his powers, gains dragon scales on the backside of the blade (In the manga, Dakki gained the dragon scales upon being forged.). If a human were to wield the katana, the continuous absorption will corrupt that person, while changing him into a demon, with scales appearing on his hands (where they are gripping the hilt) and extending to his body. A yōkai wielding the sword would be able to absorb energy to the extent that their own Yōki can restrain it, while the same would happen with a hanyō.

Powers & Abilities

 * Yōki Absorption: It has the ability to absorb the yōki from yōkai and their attacks increasing the user's power. The fake version was able to steal the entire yōki from Tessaiga's attacks, while the true version was able to steal large quantities by merely touching the Tessaiga. It should be noted that it has the potential to absorb an infinite amount of demonic energy but has a limit to how much physical punishment and amount of energy it can absorb at once which lead to its downfall. It's possible the amount it can absorb can increase with the energy it successfully absorbs but this is unknown.


 * Power Absorption: After absorbing the yōki from yōkai and their attacks, Dakki will be able to use the abilities of said yōkai or weapon. It is most likely temporary or weaker until Dakki can absorb all of the energy of the weapon or demon. If the sword fully absorbs all the energy of a weapon or creature the abilities will be permanent and the weapon will lose its magical properties, while the creature's body will be fully absorbed into the sword which was shown when it absorbed Ryūjin.


 * Yōkai Transformation: If used by a human, the blade will slowly corrupt the person wielding it, turning them into a demon. This transformation augments the users physical speed, power, and assumingly durability as dragon scales form on the users skin. Additionally, the speed of the corruption seems to be directly proportional to the amount of yōki absorbed, as Tōshū was shown to be corrupted much faster as he absorbed the demonic energy within Tessaiga.


 * : The Tessaiga's full-powered kenatsu and signature attack that could, according to legend, slay one hundred yōkai in a single strike. It was activated by sensing the fissure (or "scar") between the clashing yōki of the Tessaiga's wielder and his yōkai opponent and swinging the sword into the fissure. Dakki gained this ability after absorbing most of Tessaiga's energy.

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