Mei is one of two extraterrestrial maids and Planet Warriors assigned to Earth's protection, operating alongside her partner, Ido Toujou. They originate from an alien civilization and reside with a human named Izumi while defending the planet from monstrous threats.

Mei maintains an open romantic relationship with Ido, explicitly identified as lesbian lovers. This intimate partnership extends beyond their professional duties, including shared living quarters and sleeping naked together. Their physical connection is a practical component of their combat abilities: a kiss activates their transformation sequence into magical nurses, essential for specialized rescue operations like administering revitalizing treatments to injured creatures.

During one mission, Mei participated in neutralizing a giant lizard monster threatening Izumi. The maids engaged in close combat but were temporarily incapacitated by the monster's paralyzing aromas. After military intervention damaged the creature, they discovered its true form was a benign seal. Transforming into nurses enabled them to provide life-saving hydration before it returned to aquatic safety.

Beyond combat, their daily routines involve domestic coexistence with Izumi and shared activities like bathing with Ido. Their mascot companion, Frilly, typically accompanies them during both missions and household interactions, functioning in an observational rather than interventionist role.