Mutsumi Saotome is the sixth of nine Valkyrie sisters protecting Midgard from demonic threats. She balances her divine duties with adapting to human life. Initially reluctant, she became an idol at her sisters' suggestion, eventually gaining confidence and enjoyment despite her demanding schedule limiting school time.

She has short pink hair, violet-pink eyes, and a curvaceous figure, often wearing a black-and-white lace headband. Transforming into her Valkyrie state changes her attire to a dark violet battle uniform with gold threading and a short skirt, plus a visored white cap with small ribbons. She wields the Holy Sword "The Wings" for high-speed flight in combat.

Gentle by nature, she develops feelings for the intimidating Einherjar, Takuma Akutsu, alongside hinted masochistic tendencies. Her story involves embracing her idol career and actively pursuing Takuma's affection, openly desiring to be chosen as his primary partner despite competition from her sisters.

Within her family group, she belongs to the subgroup (with Itsuyo and Natsuki) closest to Takuma due to similar ages and shared school life, making her one of the most prominent sisters in relationship-building. Her name reflects her birth order: "Mutsu" means "six" and "mi" means "sea" or "ocean," while "Saotome" combines terms for "early" and "maiden."