Kei Asechi stands as a legendary Prism Show trainer, renowned yet controversial for her demanding methods. Her philosophy champions technical perfection above personal expression, insisting performers discard emotional connections to master the elusive Aurora Rising technique. This approach frequently sparks conflict with those who resist suppressing their emotions during performances.

She remains distant from her biological daughter, Kyoko Asechi, often treating her with coldness. Conversely, she displays greater understanding toward her adoptive son, Jun Takugawa, valuing his keen eye for spotting emerging Prism Star talent. Kei possesses her own history as a former Prism Star before retiring from the stage.

She lives alone in a remote, European-style mansion. This was once the shared home with her ex-husband, Kintaro Asechi, their daughter Kyoko, and her adoptive son Jun. The marriage dissolved due to Kintaro's obsessive focus on the Symphonia series, which endangered their family's stability. To protect herself and Kyoko, Kei initiated the divorce, resulting in Kintaro leaving the household.

Kei Asechi has dark green hair and black eyes.