Vivienne Ootori, operating under the alias Vivi, protects the city after she and her friends Silk Koharuno and Tsubomi Moroboshi perished in an accident—crushed by UFO-man during a monster attack. Consumed by guilt, UFO-man resurrected the trio by sharing his powers, binding them as new defenders. Vivienne initially resisted using her abilities, fearing indecent exposure during transformation, until Tsubomi’s failed attempt and Silk’s withdrawal forced her to step forward.

Spectators dubbed her "Ultimate Girl Kyonyuu" (Big Boobs) upon her debut, referencing her status as the most physically developed of the three. During combat, she uncovered the core power mechanic: intense embarrassment from deteriorating suits generates energy weaponizable against giant monsters. This breakthrough made her the first to effectively harness their abilities.

Vivienne fights as a close-range wrestler, serving as the team's heavy hitter. Her grappling approach diverges from Silk’s long-range energy blasts and Tsubomi’s tactical maneuvers.

A defining thread in her story involves unspoken romantic feelings for Silk Koharuno. Vivienne secretly harbored a crush but consistently failed to confess, instead supporting Silk’s own romantic pursuits—including Silk’s interest in a male photographer. One documented interaction captures the pair taking a picture together.