InuYasha is the male protagonist of the series. His exact age is unknown, but in the third movie, Swords of an Honorable Ruler, it is revealed that he is over 200 years old, despite having the appearance of a teenager. Born to a dog-demon father and a human mother, InuYasha is a dog demon/human hybrid who initially wanted to use the enormous power of the Sacred Jewel of Four Souls to become a full-fledged demon, like his older half-brother, Sesshōmaru. Fifty years prior to the main era of the storyline, though, InuYasha fell in love with the priestess Kikyō, who was given the task to protect the jewel. InuYasha changed his mind and instead, wanted to use the Jewel of Four Souls to become a human so that he could live with her, but, Naraku (an evil half demon) manipulated the both of them into believing they had been betrayed by one another. Being a shape-shifter, he used InuYasha's appearance to deceive and attack Kikyō. Before Kikyō died, however, she shot the real InuYasha with a sealing arrow that sealed him to the Sacred Tree of Ages. InuYasha remained there for fifty years, until Kagome Higurashi (Kikyō's modern-day reincarnation) pulled out the arrow and broke the seal (something she did only as a last resort to save some villagers from a demon centipede).
A few days later, in an attempt to stop a crow demon who escaped with the Sacred Jewel (which had previously been embedded in Kagome's body), Kagome shot an arrow at it and accidentally shattered the Jewel into thousands of fragments that scattered across Feudal Japan. InuYasha and Kagome then travel together to retrieve its shards. At first, he is hostile and uncooperative but Kikyō's younger sister, Kaede, now elderly and the priestess of the village, gives Kagome a necklace that restrains InuYasha from trying to steal the Sacred Jewel. Whenever Kagome gives the simple command "Sit!", InuYasha is forcibly pulled face-first to the ground due to the strong spiritual power the unbreakable necklace contains. In the beginning, InuYasha was cold and aloof towards Kagome, merely seeing her as means of recollecting the jewel fragments. As the story progressed, however, he begins to fall in love with Kagome, and yet is strained by the unexpected reawakening of Kikyō by another demon. He is extremely protective of Kagome and always worries about her safety. He often blames himself when Kagome is in danger because he feels that she would be safer if she was not with him. Because of this, he sometimes tried to force Kagome to stay in her own world. During these times, he was physically weaker without Kagome by his side. Throughout the series, his feelings for Kagome become undeniable (also obvious to his friends and enemies who often point this out), but at the same time he can't get over Kikyō, causing some indecisive behavior from him. After the reincarnated Kikyo's death, Inuyasha finally moves on and realizes that Kagome is and always was his one and only true love.
He is constantly rude and prone to bursts of violence in retaliation to the slightest thing that upsets him. He gets along with his fellow companions Shippō, Mirōku, and Sangō; however, he yells at Shippo, for his naive comments, and Mirōku, for his lecherous tendencies. He has a great hatred for Naraku because of the trap he ensnared him and Kikyō in, wishing to kill him and avenge her. Due to the beads of subjegation, InuYasha fears Kagome's anger, which will cause her to give possibly several "Sit" commands.
Eventually, Kikyō finally passes away (despite Kagome's best efforts to save her) and ascends to Nirvana. As the series progresses, InuYasha falls completely in love with Kagome, realizing that she is the sole reason that he is no longer lonely or unhappy. During the final battle within the sacred jewel, he states that she was born for him and he for her. In the anime adaptation, they share a kiss. After Kagome wishes the jewel away with him at her side, they are separated for three years. However, InuYasha and Kagome are eventually reunited, and later married.
The name InuYasha means "Dog Yaksha". Historical Japanese figures featured names ending in "yasha" (夜叉), a non-native term (Chinese characters meaning here is phonetic and gibberish) borrowed from Chinese in turn phonetically borrowed from Sanskrit.