Kirara is the nekomata companion of Sango, the yōkai exterminator (退治屋, taijiya) that hails from a mountain village of other exterminators. Despite her yōkai blood and appearance, she is fiercely loyal to Sango and her friends and has been in Sango's family for generations. She has taken a particular shine to Shippō, keeping the young kitsune company when her presence is not required in battle, and she has aided InuYasha on occasion by teaching him how to wield his sword, the Tessaiga. Kirara is a formidable opponent, and she displays her strength and agility on several occasions. She also seems to have an unusual resistance to most poisons but is still susceptible to Naraku's Miasma attack. She is also able to pass through certain kinds of barriers.

Kirara usually appears as a tiny and cute feline no larger than a kitten with white fur, various black markings, large red eyes, and two tails, but her true form is a large Saber toothed like yōkai-cat. She has long, saber fangs and the fire that wreaths her legs and tails. She is also able to fly in her larger form and can easily carry three people on her back.

It is strongly hinted at in the anime (but not in the manga) that Kirara, or one of her ancestors, was at one time the companion of Midoriko, creator of the Shikon no Tama (The Jewel of the Four Souls). As the taijiya village was built near the site of the legendary battle between Midoriko and the yōkai that nearly consumed her, this is a logical assumption.