Ms. Sanada is the chief maid of the Valhalla royal family, exhibiting unwavering loyalty to Princess Valkyrie. Discovering Valkyrie transformed into an eight-year-old after transferring half her soul to Kazuto Tokino, Sanada developed a deep affection for the childlike princess's adorable nature, declaring herself a "Valkyrie fundamentalist." She instantly recognized Kazuto as Valkyrie's official fiancé and became a fervent supporter of their developing romantic relationship, actively encouraging their union.

To protect Valkyrie and eliminate perceived romantic rivals near Kazuto, Sanada employed extreme measures. She notably used her "Cat Ear Gun" (also called the "Cat-Girl Ray Gun") to transform numerous girls in the city into a brainwashed army of catgirl maids solely for being near Kazuto. This incident escalated when she targeted Akina Nanamura, triggering a destructive conflict involving Hydra. Sanada maintained these transformed maids indefinitely, summoning them with a whistle when needed for assistance, though she typically neglected to remember their individual names and never reversed their brainwashing.

During the third season, Sanada adopted a superhero identity to further aid Valkyrie and Kazuto. Her background hints at a fondness for Valkyrie Ghost, an entity from the second season. Sanada's actions consistently prioritized Valkyrie's safety and romantic interests with Kazuto, even when her methods caused significant collateral damage or ongoing complications for others.