Saki Mitsurugi

Saki Mitsurugi, real name Grigio, is a mysterious woman who opposes the Ultra brothers Rosso and Blu and the secondary antagonist of Ultraman R/B.

History
Saki Mitsurugi was originally Grigio, the younger sister of Ultras Rosso and Blu. Grigio and her brothers once fought Reugosite to defend the Earth from it and managed to drive it away at the cost of Rosso and Blu's lives. Since then, Saki vowed to destroy Reugosite at any cost. Saki Mitsurugi first appears after Ultraman Orb Dark defeats Horoboros to claim its R/B Crystal. She later summons Horoboros during a confrontation between Orb Dark and Ultramen Rosso and Blu and the monster defeats the Ultras.