Persephone the First, also known as Kasugai Persephone, is the mother of Persephone II and a former teacher at Makai Elementary School where she instructed Jashin-chan, Minos, and Medusa. Originally from Heaven, she departed its strict confines, later residing in the Underworld as Hades' wife before ultimately moving to the human world. Her appearance shifted from silver hair and crimson eyes during her teaching career to greenish-blonde hair after her marriage. In the human world, she dresses in a white long-sleeved blouse featuring a bright pink pearl on the collar, a long blue skirt, and brown boots.

Kindhearted, particularly with children, she works as a caretaker at a human orphanage. Yet she enforces rules strictly, exemplified by punishing Jashin-chan for cheating. Persephone possesses a fragile constitution; polluted air or unstable magic triggers coughing or vomiting blood, a trait inherited by her daughter. Her relationships include a fractured bond with her childhood friend Lierre from Heaven. Persephone longs to reconcile and occasionally leverages Lierre's childish behavior for amusement.

She deeply loves her daughter, Persephone II, though initially spent little family time together. She sent Persephone II to the human world to find Jashin-chan, unaware of the dangers, leading to their eventual reunion there. Persephone respects her daughter's choice to be called "Persephone II" over her birth name "Picoletta," inspired by a bathroom air freshener. She uses "Ni-sei" formally and "Picoletta" privately. After moving to the human world, she demonstrates increased care, spending time with her daughter whenever possible.

Working at the orphanage while immersing herself in human culture, she maintains her nurturing role.