Ayame is a wolf demoness who was rescued by Koga from the Birds of Paradise when she was very young. He promised her on the night of a lunar rainbow that he will marry her when she will return from the northern mountains after completing her training.
Ayame finds Koga again after many years and she reminds him of his promise, but he tells her that he wants to marry Kagome as she can sense sacred jewel shards which can make him strong enough to find Naraku who destroyed his wolf tribe. He must avenge their death first.Later, her tribe is attacked and Koga comes to the rescue. This starts the Shichinintai saga.
Ayame is quite strong herself, and she can throw grass and leaves which can slice through demons. She once helps save Hakkaku and Ginta – two of Koga‘s friends.
An interesting fact – Ayame was made specifically for the anime, and was not in the manga!