She is the "other self" of Kagari Izuriha.
Chariot is a pale skinned female wearing a dress with black and white tones. She wears a large spiked crown on her head, as well as claw-like gloves. Most notable is her choice of footwear: she wears black, metallic thighhighs with black and yellow wheels that can be used as cutting weapons.

Like all of the "other selves" in the anime, her yellow eyes have a circular pattern in them.

Her weapons of choice are a Sword and Shield. Chariot has been shown capable of using the wheels attached to her legs as a weapon against Black★Rock Shooter, as well as a giant spider monster to ride on.

She is said to have a cold gaze, as it feels as if she is piercing into your heart. Chariot is shown to be rather brutal to Black★Rock Shooter when she enters her area in the Otherworld, and when she tries to save Dead Master from Chariot. Chariot also shows some sadistic joy in brutally beating Black★Rock Shooter, which may reflect on how Kagari hates Mato for trying to be friends with Yomi in the real world.
(Source: Black★Rock Shooter Wikia)