Ms. Sanada is chief maid to Princess Valkyrie of Valhalla, possessing unwavering loyalty and dedication. She instantly accepted Kazuto Tokino as Valkyrie's official fiancé upon the princess's arrival on Earth, a stance maintained even after Valkyrie transformed into an eight-year-old child. Sanada finds this form endearingly cute and actively supports the romantic bond between Valkyrie and Kazuto.

To protect Valkyrie, Sanada employs extreme measures, including her "Cat Ear Gun" (or "Cat-Girl Ray Gun"). This weapon transforms human girls into permanently brainwashed catgirl maids, creating an obedient workforce under her command. She deploys it against perceived threats to Valkyrie's relationship, notably targeting Akina Nanamura after misinterpreting a friendly exchange with Kazuto as romantic interest. This incident escalated into a large-scale conflict with Princess Hydra, causing significant city property damage. The transformed girls remain brainwashed, wear maid outfits, and respond to Sanada's summons via a specialized whistle, though she typically doesn't recall their names.

Sanada's loyalty manifests unconventionally. During the third season, she adopted the superhero persona "Cat Eared Maiden" to covertly assist Valkyrie and Kazuto. Valkyrie admired this alter ego, prompting Sanada to gift her a handmade figure. Her protective instincts often conflict with characters like Hydra, and her actions frequently exacerbate situations. A subtle fondness for Valkyrie Ghost is hinted in her interactions.

Her role provides comic relief through exaggerated devotion while offering genuine emotional support to Valkyrie through challenges like multiple wedding postponements and the princess's eventual physical split into separate child and adult entities. Sanada consistently prioritizes Valkyrie's well-being, disregarding collateral damage or social norms.