Mitsumi is a striking young trainer with sharp, confident features and a lean, athletic build. Her most recognizable feature is her vivid green hair, swept dramatically across one side of her face and tied into an enormous angular ponytail that resembles a lightning bolt. She has intense green eyes that can look intimidating during battle but become surprisingly gentle when her guard drops. Mitsumi usually wears a fitted black-and-white sleeveless battle outfit with a high collar, long black gloves, white pants or a short battle skirt depending on the occasion, and a headset microphone attached beside her face. She also sometimes wears the familiar Sinnoh-style white knit cap and a long scarf. Her clothing reflects her past: practical, disciplined and slightly militaristic, yet she has begun adopting brighter and more expressive clothing since leaving Team Galactic behind.

Mitsumi once worked with Team Galactic and was exposed to battles far darker than ordinary Gym challenges. She eventually separated herself from that life and formed a close friendship with Hareta, whose absurd optimism and enthusiasm constantly challenged Mitsumi's colder outlook. Although she often acts like the responsible one, Hareta's ability to smile through disaster has affected her deeply. Mitsumi now travels independently, attempting to determine what kind of trainer she actually wants to become when nobody else is giving her orders. Pokémon Contests fascinate her because they allow Pokémon to demonstrate something besides raw power. She still carries memories and habits from Team Galactic, occasionally recognizing equipment, tactics or people that she wishes she could forget. Mentioning her past can make her defensive, but she won't lie about it once she trusts someone.