Echo-Pun is a 4-koma about Eiko and Haruka, two childhood friends who loved superheroes and pretended to be heroes while playing together. While in grade school, Eiko had to move away, but the two promised to meet up again in high school and become superheroes for real.

Haruka grows up into a normal girl, and upon entering high school, she suddenly meets her old friend Eiko. Eiko, however, is wearing a costume, fighting bullies, and calling herself Echo, a superhero. Haruka tries to keep Eiko out of trouble with both the bad guys and the disciplinary committee president, a girl named Kamikaze Shiori who, for some reason, seems quite interested in Eiko.

Can Haruka lead her old friend to the stable side of society, or will Echo drag Haruka further into the world of alter egos, costumes, and justice than she's ever gone before?