Boku Dake ga Shitteiru

Nakamura-san, who sits next to me in class, is a gal with long nails, a smartphone, and a penchant for fashion. But I'm the only one who knows her secret identity. Nakamura-san is a gal-hero who protects the world!

(Source: Dengeki Daioh G, translated)

Note: Originally published in Dengeki Daioh G vol. 125.