Ayame is a fairly small woman who wears dark clothes and carries two short blades. She looks as you'd expect a female ninja to look, since the Tenchu series usually doesn't exaggerate or stylizes Ninja with long red scarfs and such. She has a lot of attitude that normally doesn't fit her position or life style. Opposite of Rikimaru she might show a lot of her emotions during battle.
The Tenchu series always has multiple characters and Ayame is usually the fastest in all the games. In Tenchu: Fatal Shadow Ayame is the main character (Since Rikimaru is not present) and a new female character named Rin gets introduced. The two characters, in that game, are very similar and Rin might be a bit faster but besides Fatal Shadow Ayame is always the swiftest.
Ayame was picked up by a Ninja named Shiunsia in Kyoto while she was very young. Shiunsai found the girl in a battle torn village as she watched the bodies float down the river. The only thing the girl could recall was her name and her age. She had alot of talent but she also had a bad attitude. She became a Ninja when she was twelve and was given the name Ayame.
The other Ninja Ayame trained and grew up with were Rikimaru and Tatsumaru. She cared for them both but had feelings of love for Tatsumaru, who was going to be the next leader of the Azuma Ninja. Unfortunately Tatsumaru was knocked out and was brain washed by the enemy in Tenchu 2. They were called the Burning Dawn and were lead by Lady Kagami. During his time with the enemy Tatsumaru murdered Master Shiunsai, who raised and trained them, and he scarred Rikimaru's face.
In the end it was Ayame who had to defeat Tatsumaru and once she did she handed Rikimaru the Izayoi(a sword handed down to the current leader of the Azuma Ninja clan. Tatsumaru had it when he was brain washed). Finally, she was ready to end her life after loosing Tatsumaru, but she remembered she still had a reason to go on and it was Princess Kiku. Princess Kiku was the daughter of the Lord that the Azuma served, and ever since Kiku's mother was killed Ayame thought of her as a little sister. Using the Princess as motivation she vows to live on and become stronger.
Since the events of Tenchu 2, Ayame has become stronger and lives through almost anything. Even at the end of Tenchu 1 when she thought Rikimaru died she simply planted his sword into the ground as a makeshift grave and went on.