Magatsuhi is the youkai responsible for Midoriko's demise, locked in an eternal battle with her soul within the Shikon Jewel. Similar to Naraku, Magatsuhi was born from a corrupted human who desired a priestess and allowed demons to consume his body. However, unlike Naraku, who maintains a humanoid appearance, Magatsuhi’s true form is far more monstrous. First appearing as a mummified corpse of an unnamed but colossal demon in manga chapter 89, Magatsuhi's identity is later revealed. It escapes the jewel temporarily, creating a humanoid body using parts from Naraku, though this form is quickly destroyed by Sesshomaru and InuYasha.
In chapter 555, InuYasha witnesses Magatsuhi fighting Midoriko inside the Shikon Jewel. Magatsuhi claims that if Kagome makes a selfish wish on the Jewel, she would take Midoriko's place in the endless struggle, while Naraku would replace Magatsuhi. Disbelieving Magatsuhi, InuYasha attacks it to reach Kagome. Ultimately, both Magatsuhi and Naraku are vanquished when InuYasha slices through the light in the darkness within the Shikon Jewel using Meidou Zangetsuha, transporting him and Kagome outside the jewel. Kagome then makes the correct wish: for the Shikon no Tama to vanish forever. The jewel shatters and disappears, returning InuYasha and Kagome to solid ground.
