Asuka Asagi transforms into the magical girl Earth Nana, commanding earth-based elemental powers. She wields a bow and arrow as her primary weapon in battle against monsters. Polite and proper in demeanor, her conduct reflects her disciplined upbringing as the heir to a family-run convenience store. This background frequently leads her to admonish her teammate, Itaru Washioka, for perceived recklessness.

Visually linked to the color green, symbolizing her earth connection, her design features light green hair styled in a ponytail secured by a berry-themed clasp and matching light green eyes, exemplifying the "Curtains Match the Window" trope. Upon transformation, her hair intensifies to a brighter green, demonstrating the "Power Dyes Your Hair" effect.

Within her trio of magical girls, Asuka embodies the "Girly Girl" archetype, contrasting directly with Itaru's tomboyish traits. Her personality and elemental theme consistently align with the "Proper Lady" trope, emphasizing her grounded, nature-aligned qualities.