The protagonist of the series, Inuyasha is the younger hanyou son of Inutaishou. He was searching for the Shikon no Tama to make himself a full youkai, and fell in love with the priestess who was guarding it, Kikyou. He agreed to use the Shikon no Tama to become a human so that they could live together, but Naraku set them up to believe they had betrayed each other. Kikyou died and Inuyasha was pinned to a tree for fifty years.

Higurashi Kagome, a school girl in the modern age who is the reincarnation of Kikyou, fell down a well in her back yard which sent her back 500 years to the Sengoku Jidai. She released Inuyasha from the tree and later shattered the Shikon no Tama with her arrow. Inuyasha and Kagome team up to find the shards, because Kagome has the ability to see them and Inuyasha has the power to get them back. They quickly meet and join up with Shippou, a young kitsune, Miroku, a lecherous monk, and Sango, a demon exterminator. All of them have a reason to find and destroy Naraku, save Shippou and Kagome, who are sort of along for the ride.

Inuyasha doesn't have any memories of his father (who died when he was still a baby, or if you take the movie's word for it, on the night he was born.) From what we’ve seen, he seems to take after him in both personality and appearance (Inuyasha and his father have thicker eyebrows than Sesshoumaru, and the strips on Inuyasha’s face when he's in his full-demon form are the same his father has). He inherited the Tessaiga from his father. Because he's a hanyou, on the night when there's no moon he turns into a human and he turns into a full youkai when he lets go of the Tessaiga.