Midoriko was a miko centuries before the events of the series, when the shoguns served as de facto rulers over most of Japan. As a priestess she was well known for her immense spiritual powers and abilities, more specifically her ability to purify a yōkai souls and spirits, rendering them powerless. It was because of this power that Midoriko was both hated and feared by demons.
In her final battle, Midoriko was ambushed by many yōkai. The battle lasted for seven days and nights and eventually a yōkai (created when many yōkai possessed a mortal man who secretly desired Midoriko, à la Naraku) captured her in its jaws. Midoriko, in one final attempt to defeat the yōkai, pulled its soul into her body—fusing it with her own soul—and then expelled them both simultaneously. Both yōkai and Midoriko died, but their souls combined to give birth to the Shikon no Tama. Midoriko and the demon remained imprisoned within the Jewel and continued to battle.
During the Story Edit
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 Myōga (however, it could just have been Myōga 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 Kikyō instead. In the ending, when Inuyasha entered the jewel, he finally saw Midoriko herself and witnessed her to help him fighting and defeating a huge amount of demons then disappearing and never returning.
In the manga, Magatsuhi's desire expressed by Naraku dissolved forever her soul in order to prepare the place for Kagome. In fact, after her disappearance, the demons tells to Inuyasha that her battle with them has lasted for the hundreds of years since the Shikon no Tama was born, and Kagome will continue it from here. Furthermore, after her disappearance, the huge spider web with Naraku's dead soul instantly appears.
Instead, in the anime series, after Kagome makes her wish to destroy the jewel and also stop its plan to replace Magatsuhi and Midoriko with Naraku and herself, 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 to the afterlife.
Powers and Abilities Edit
As a priestess, Midoriko had extremely high power-levels of spiritual power, strength and energy being representing the purity of the Shikon no Tama. She was also thought to have the equal strength and power of one hundred samurai.
- Immense Spiritual Powers and Abilities: Midoriko had exceedingly strong and powerful spiritual power and abilities. Her spiritual powers and abilities alone could purify hundreds and hundreds of demon souls and spirits all at once, thus rendering them utterly powerless and harmless.
- Purification Abilities: Midoriko was capable of infusing her exceedingly strong and powerful spiritual powers and abilities into her sword and purify twenty demons at once. Her purification abilities are so strong enough to completely purify Naraku's miasma as shown when Kikyō fused Midoriko's soul unto her body to heal miasma inflicted wounds that Naraku inflicted upon her body.
- Spiritual Possession: Midoriko had the amazing power and ability to possess a person.
- Enhanced 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 with out needing to rest.
- Barrier Creation: Midoriko has the ability to create very powerful barriers, even though she was within the Shikon No Tama she was still be able to maintain the barrier on the entrance of the cave where the Shikon no Tama was created and even withstand the barrier-breaking Red Tessaiga.
- Sword: She is seen carrying and using a large sword as a weapon, it could be that she had infused her immense spiritual power and ability into her sword to slay demons.
- Midoriko probably lived somewhere between 1203 and 1333 when the shoguns and their shikken regents were at the peak of their power.
- 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 the fourth movie InuYasha: Fire on the Mystic island, 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 the fourth movie, as she was a clone.
- How her name is pronounced is changed in the English Dub of the Final Act; in the original series, it was pronounced "mee-door-e-ko", now it's pronounced "meed-oh-ree-ko".