Fifty years ago he was put into statis by an enchanted sealing arrow from Kikyou. Inuyasha is after the Shikon no Tama. This is because if he gets the Shikon no Tama, he can become a full demon, with full demonic powers. Inuyasha is brought out of his statis of fifty years by Kagome. Because she is believed to be a reincarnation/descendent of Kikyou, she is able to pull the arrow out, ending the enchantment and set Inuyasha free. Although it appears at first that Inuyasha hated Kikyou, we find out it isn't entirely true...
Inuyasha travels with Kagome, looking for the pieces of the Shikon no Tama. Along the way they make new friends, and companions join their travels too.
Inuyasha has several attacks. The number of his attacks increase as his sword, the Tessaiga, increases in power, reaching its full potential. The following are his attacks (in the anime) so far...
No matter the situation, Inuyasha protects Kagome. Even though he always says she's bothering him by being there, it is her presence that makes him stronger. When Kagome isn't there, Inuyasha doesn't seem to reach his full potential. Whenever Inuyasha is in human form, the Tessaiga remains a regular sword, and doesn't transform. Usually Inuyasha doesn't like to think he is human once a month, and usually goes beyond his limits, getting quite banged up in the process...
When it comes between Kikyou and Kagome, Inuyasha has an internal conflict about who is the one he cares about and loves. Sometimes he thinks it's Kikyou, other times Kagome. Time will have to tell us who he chooses. Either the real, living Kagome, or the resurrected, half-living Kikyou...either way, Inuyasha definitely has human emotions, making him a kind, caring half demon.
Inuyasha's voice is done by Yamaguchi Kappei R(Meitantei Conan, One Piece, Ranma 1/2, Gravitation, Angelic Layer)
When defeating Jibugarasu (the bird demon creature), the arrow that defeated the demon ended up splitting the Shikon no Tama into an unsaid number of shards. Now, Kagome and Inuyasha are looking for the shards. Kagome's reasoning is that she doesn't want anyone to get hurt from the demons who become more powerful after they obtain a shard or two of the Shikon no Tama. She uses a bow and arrow to fight against demons. Kagome also has a mystical power, reminiscent of Kikyou's, or any Miko's, power.
Kagome often goes back and forth between her world and the Warring Time Period. She brings lots of useful things, such as her bike or a first aid kit, but as time goes on, she goes back less and less often. The excuse given to her school and friends is that she is having health problems with her "frail body." This excuse was made up by Kagome's grandpa.
At first Kagome said she didn't like Inuyasha, and even when asked what her ideal guy would be, she thought to herself that Inuyasha's opposite would be perfect. But now...her feelings have changed. Kagome cares for Inuyasha, but she knows that he still thinks of Kikyou. Kagome isn't convinced yet that Inuyasha cares for her as well. Time will reveal their situation, but for the time being, Kagome and Inuyasha always have little quarrels, nothing serious, but not unusual of a couple...