Mei Izumi is an 18-year-old idol from Saitama, currently in her third year of high school. She stands 162 cm tall, weighs 51 kg, and possesses light brown hair with measurements of 90-58-88 cm. Her blood type is O, and her horoscope sign is Leo. Her hobbies include hanging out with friends and listening to recent music; she is notably skilled at talking on the phone for hours.

Naturally upbeat, optimistic, and broadly approachable, Mei is easy to talk to, though she sometimes struggles with complex concepts. This friendly nature sharply contrasts with her significant stage fright, which causes her voice to become small and her words to falter during performances. To overcome this, a producer suggested adopting a cool, mysterious on-stage persona requiring minimal speech and a steady, husky voice instead of her natural bubbly tone. Mei accepted this strategy, finding it effective for continuing her idol career despite the divergence from her everyday behavior.

She is a core member of the unit Straylight alongside Asahi Serizawa and Fuyuko Mayuzumi. Within the unit, Mei shares a sister-like bond with Asahi, who appreciates the familial dynamic. Her straightforward nature allows her to interact comfortably with Fuyuko regardless of the latter's moods, earning Fuyuko's respect.

Mei comes from a large family, with four siblings: an older brother, an older sister, a younger brother, and a younger sister.