Mizune Masaki originates from Masaki Village and is a distant cousin of Tenchi Masaki. As the great-granddaughter of Yosho and his first wife Kasumi, she possesses the most direct and purest imperial Masaki bloodline among the village's native members. Despite this prominent lineage, Mizune displays an immature demeanor and lacks preparation for the potential responsibility of representing Earth's Masaki family once Yosho's existence becomes public knowledge. She serves as one of Lady Seto's ladies-in-waiting within Minaho Misaki's subgroup. Mizune periodically returns to Masaki Village from space, having resided there when Kiyone Masaki and Nobuyuki Masaki first met. Her visits to Earth occur frequently enough that her cousin, Kai Masaki, recognizes her immediately. Mizune maintains a friendly connection with Seina Yamada, though Lady Seto has ordered her to avoid contact with him until after his graduation. During the events of "Tenchi Muyo! GXP Paradise Starting," Mizune was assigned to lead a construction crew on Tabletop Island. Fearful of admonishment for her poor performance in this task, she fled into space, taking Fuka Masaki with her. Tomi Masaki subsequently replaced her as the project leader. The destination or outcome of her flight remains unspecified. Her surname, Masaki, combines "masa" (meaning "straight grain," "spindle tree," or "right/proper") and "ki" (meaning "tree" or "wood").