Midoriko

Midoriko (翠子, Green Child) is a minor character in story of InuYasha, but has a huge impact on the overall plot.

History
Midoriko was a miko many years ago. She was well known for being very powerful and her ability to purify a yōkai soul. It was because of this, however, that her fate was sealed.

In her final battle, Midoriko was ambushed by many yōkai. The battle lasted for 7 days and nights and eventually a yōkai, created from the possession of a man, who secretly desired Midoriko, by many yōkai, got her in its jaws. Midoriko, in one final attempt to defeat the yōkai, forced out the yōkai's soul and her soul from their respective bodies. Both yōkai and Midoriko died, but their souls combined to create the Shikon no Tama.

Midoriko and the demon remained imprisoned within the Jewel and continue to battle, until Kagome made a wish to make the Jewel disappear forever.

Current Story
Although many years have passed, her body exists (in crystallized form in the anime, as a mummy in the manga) in the Yōkai Taijiya Village (The Demon Slayer Village). She made a cameo, in which she saved Myoga (however, it could just have been Myoga seeing things). It is said that Midoriko and yōkai are still fighting inside the Shikon Jewel.

As the story continues, her soul and the yōkai were split from the Sacred Jewel, as it had intentions to use Naraku, Kagome, and Kikyo instead. However, she and the yōkai were finally banished when Kagome wished for the Shikon no Tama to disappear forever.

In the manga, what became of Midoriko was never shown. However, in the anime series, after Kagome makes her wish, Midoriko ceased her fighting and disappeared along with the demons she fought, implying that her battle had finally ended and she was allowed to move on.

Powers and Abilities
As a priestess, Midoriko had extremely high levels of spiritual power. She was also thought to have the equal strength and power of one hundred samurai.
 * Purification: Midoriko was capable of infusing her exceedingly strong and powerful spiritual powers and abilities into her sword and purify twenty demons at once.
 * Possession: Midoriko had the amazing power and ability to possess a person.
 * Stamina: Midoriko had extremely high stamina as she was able to fight many demons (who had all merged into one single demon named Magatsuhi) for seven days and seven nights.
 * Swordsman: She is seen carrying and using a large sword as a weapon, it is assumed she knows some swordsmanship. It could hinted that she had infused her immense spiritual power and ability into her sword to slay demons.
 * Spiritual Powers: Midoriko had exceedingly strong and powerful spiritual power and ability. Her spiritual powers and abilities alone could purify hundreds of demon souls at once, thus rendering them utterly powerless.

Anime/Manga Difference

 * It is hinted that Kirara fought by Midoriko's side in the anime, while in the manga, it had made no hints towards this.
 * In the manga, Midoriko's fate after Kagome made her wish for the jewel to disappear forever was never shown. In the anime series, after Kagome makes her wish, Midoriko ceased her fighting and disappeared along with the demons she fought, implying that her long battle has finally ended and she is allowed to move on.
 * In the anime, InuYasha, Kagome, Shippo, Miroku, and Myoga are unable to enter the cave and they only can get in after Sango tells them how. In the manga, they are able to walk in without her.

Trivia

 * Despite being responsible for the whole story of InuYasha (she was responsible for the existence of the Shikon Jewel), she has a really minor role in the actual story.
 * In InuYasha Movie 4, the clothing that the fake Kikyo is wearing looks very similar to Midoriko's clothing.
 * Midoriko is the only priestess shown in the story that wields a sword. Not counting the Kikyo in Movie 4 as she was a clone.