|Title||Demon Lord of Japan|
|Faction||The Shikon Empire|
"You thought you could destroy me! You fools I allowed you to destroy the shikon jewel so that I would be free from it! I will conquer this land and rule as the master of all it's demons!"
Template:Translation is the yōkai who killed Midoriko and whose soul with whom she continuously battles inside the Shikon Jewel. Magatsuhi was created by numerous demons who formed into one demon in order to kill Midoriko. Magatsuhi's true form is much more monstrous.
Magatsuhi is first seen in manga chapter 89 as the mummified corpse of an unnamed but massive demon. He is the demon who fought and died with the ancient priestess Midoriko hundreds of years ago.
Later in the manga, the demon's name is revealed to be Magatsuhi, and Naraku helps him manifest in physical form so that Magatsuhi can help him complete the Shikon Jewel. Magatsuhi seems to fear Kagome's spiritual power and seals away her true strengths to prevent her from purifying him. Magatsuhi's first mission after coming to life is to defile and obtain Kohaku's shard but he is obstructed by Sesshōmaru, whose sword Magatsuhi fears, as it can kill him. Magatsuhi flees after being injured in the fight (having lost the flesh Naraku lent him), and along with Naraku tricks Sesshōmaru into leaving Kohaku alone with a fake Magatsuhi.
He suceeds in kidnapping Kohaku, made unconscious by Magatsuhi's defilement of his shard, and severely injuring Sango and Miroku who tried to stop the demon. He remained in control of Kohaku, tormenting the boy with visions of his past, until Kohaku managed to awaken and break free of Magatsuhi. Kohaku then attempted to drive the demon from his body, even at the cost of his own life. Magatushi curses him and fights back until being slashed by Sesshōmaru, who has returned after realizing he was tricked. Sesshōmaru attempts to kill Magatsuhi but he escapes at the last moment, having hidden his essence in Miroku, who he poisoned.
Magatsuhi then appears inside Naraku's enormous body in the final battle, possessing Inuyasha and trying to kill Rin and Kagome. Sesshōmaru mocks him, taunting Inuyasha was the worst person to possess and Magatsuhi finds Inuyasha fighting back at his control. He is driven from Inuyasha's body and after trying to take over Kagome, is killed by Sesshōmaru.
In chapter 555 in the manga, Magatsuhi's spirit is combating Midoriko inside the Sacred Jewel. However, he is split into the many demons that formed him. Magatsuhi states that if Kagome were to make a selfish wish on the Shikon Jewel, Kagome would replace Midoriko in the eternal fight in the Jewel and Naraku would replace him.
Inuyasha refuses to believe Magatsuhi, and proceeds to attack it in an attempt to reach Kagome and save her.
In the manga ending, Magatsuhi and Naraku were destroyed forever by Inuyasha when he cuts the point of light in the darkness inside the Shikon Jewel with Meidō Zangetsuha and arrives in the Meidō outside the Jewel to save Kagome. This point of light was the key left by Kikyo before dying to kill Naraku and destroy the jewelry evil. In fact, with Inuyasha's attack, the Jewel's shimmering completely stops. The rest of the Jewel breaks and then disappears when Kagome makes the right wish for it to be taken out of existence.
Instead, in the anime version, when Kagome makes the right wish, Magatsuhi (the demons that form him) is enveloped in light, along with Midoriko and Naraku, finally putting an end to his, the Jewel's, and Naraku's evil. Inuyasha and Kagome are transported back to earthen ground.
As the embodiment of darkness of the Shikon Jewel, Magatsuhi is pure evil, perhaps even more so than Naraku himself. He views every other single being, living or not, as inferior to him, repeatedly calling Sesshōmaru weak and disliking any comparisons of him to Naraku. He sneers at courage and self-sacrifice as seen when badly injuring Miroku and Sango, taunting Miroku for absorbing Magatushi's deathly poison to save Kohaku from him and sneering that he will die. He also is sadistic, promising Sango he will return her brother as a corpse once he is through with him. However, like traditional villains, his arrogance makes him underestimate his opponents which usually costs him to lose a battle.
After the events of the series life returned to normal however Magatsuhi managed to preserve a portion of his spirit allowing him to return to life. Once he had succeeded in doing this he forced demons to fight each other inorder to construct himself a new body. After he had constructed himself a new body he amassed a army of demons and secretly founded his own empire. He eventually attacked Inuyaha and his friends systimatically killing them off one by one.
- Immense Demonic Power: Representing the evil of the Shikon Jewel, Magatsuhi is terribly powerful, having backed both Inuyasha and Sesshōmaru in demon form into a corner. His power appears to exceed even Naraku's, calling himself a league far beyond his.
- Shapeshifting: Magatsuhi has the ability to transform a part or his entire body into a plethora of large, thick tentacles capable of deadly constriction as well as used for impaling enemies. Magatsuhi has no definite form. Like Naraku, he, too, is an an amalgamation of demons, briefly borrowing flesh from Naraku to assume a physical form in the material world.
- Immortality: Magatsuhi shows incredible resilience on the battlefield, shrugging off a decapitation as if it was nothing and in his spirit form, is immune to all forms of physical combat.
- Corruption: Magatsuhi's darkness is so vast and dense that a simple stare corrupted and temporarily knocked out Kagome.
- Possession: Magatsuhi can possess another's body. He did this to Rin, Inuyasha and Kohaku.
- Miasma: Magatsuhi's miasma is one of the strongest if not the strongest in the entire series. His miasma is strong enough to seriously injure Sesshōmaru who is very much immune to poison and is of course fatal to humans. His miasma almost kills the monk Miroku who, if not for Magatsuhi fleeing from Sesshōmaru through Miroku, would have certainly died.