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Plot
Seven years ago, Yuto Amakawa's parents died in a car accident, leaving him alone without a single relative, the only item left of his family being a strange and mysterious amulet given to him by his late grandmother. Ever since then, his childhood friend Rinko Kuzaki and her parents has cooked and taken care of him. His life takes a drastic turn on his 16th birthday when he meets Himari, a cat spirit samurai girl. Himari reveals to him that some of his ancestors were part of the twelve Demon Slayer families that have been slaying demons since the feudal era. She has sworn an oath to protect Yuto from the demons that are out to kill him, but Yuto's allergy to cats makes it somewhat difficult to deal with.
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As the series progresses, Yuto and the group encounter some powerful ayakashi, with some of them being allies, and Yuto eventually makes a life-changing decision to fight for his belief of coexistence between human and ayakashi.
Terminology
- Demon Slayers ( Onikiriyaku ):
- Humans with supernatural powers and abilities with the duty to slay ayakashi, which has been their primary purpose for hundreds of years. The Demon Slayers were established by the feudal lords who opposed the ayakashi and because of this, most of the surviving ayakashi bear a grudge against them for their near-extinction. The Demon Slayers consist of twelve families, each family having their own unique powers and abilities, such as the Amakawa Family with their Light Ferry ability and the Jinguji Family with their dark magic. Out of the twelve families in feudal times, less than half of the families remain in existence in present times. Each Demon Slayer family is sorted by rank, with the Jinguji Family being at the bottom (#12) and the Tsuchimikado Family at the top (#1).
- Ayakashi :
- The demons and spirits based on Japanese mythology and folklore. They once coexisted with the humans until the Demon Slayers arrived and killed most of them. As a result, the surviving ayakashi bear a deep hatred towards the Demon Slayers. Some ayakashi, like Himari and Shizuku, can assume human forms to blend in with society (though Himari comments that most do not like human cities), and some ayakashi can cast barriers and spells using their yōki ( "Demon Energy").
- Among the ayakashi are three powerful ayakashi known as Japan's Three Great Evil Demons ( Nihon Sandaiaku Yōkai, consisting of Shuten-dōji, Tama, and Emperor Sutoku, who has yet to appear in the series. They were sealed by humans in ancient times and parts of them were spread throughout Japan until it was broken by Tama's awakening and Shuten-dōji's revival. It remains unclear if Emperor Sutoku has been freed after the seal was broken. Although many ayakashi in Omamori Himari serve as antagonists, there are some who serve as allies. )