Oni

Oni is a japanese word for huge, beastly demons.

Onigumo

Onigumo was a bandit that was badly burned by a fire. He could not move and lived in a cave, and Kikyou came to care for him every day. Onigumo began to desire Kikyou so much that he allowed may demons to enter his body and he became to demon Naraku.

Osuwari

This is the Japanese word used to tell a dog to sit. It's the command Kagome uses with Inuyasha which makes him fall to the ground.