Long ago, in the "Warring States" era of Japan's Muromachi period (Sengoku-Jidai, approximately 1467-1568 CE), a legendary doglike half-demon called 'Inu-Yasha' attempted to steal the Shikon Jewel, or 'Jewel of Four Souls' from a village, but was stopped by the enchanted arrow of the village priestess, Kikyo. Inu-Yasha fell into a deep sleep, pinned to a tree by Kikyo's arrow, while the mortally wounded Kikyo took the Shikon Jewel with her into the fires of her funeral pyre. Years Passed.

Fast forward to the present day. Kagome, a Japanese high school girl, is pulled into a well one day by a mysterious centipede monster, and finds herself transported into the past, only to come face to face with the trapped Inu-Yasha. She frees him, and Inu-Yasha easily defeats the centipede monster.

The residents of the village, now fifty years older, readily accept Kagome as the reincarnation of their deceased priestess Kikyo, a claim supported by the fact that the Shikon Jewel emerges from a cut on Kagome's body. Unfortunately, the jewel's rediscovery means that the village is soon under attack by a variety of demons in search of this treasure. Then the jewel accidentally shattered into many shards, each of which may have the fearsome power of the entire jewel.

Although Inu-Yasha says he hates Kagome because of her resemblance to Kikyo, the woman who 'killed' him, he is forced to team up with her when Kaede, the village leader, binds him to Kagome with a powerful spell. Now the two grudging companions must fight to reclaim and reassemble the shattered shards of the Shikon Jewel before they fall into the wrong hands.

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The introduction information above was taken directly from the Inuyasha Anime Artbook by Rumiko Takahashi