A quartet of comedic rock stars called "Mountain Horse" unexpectedly gain superhuman powers after listening to a rock concert they opened for. The powers themselves are not very strong, but enough that they get noticed by Fuurouta of the Superhuman Bureau, and a publicity agent named Fugimoto. After overhearing Fugimoto's plan to sell chocolate with an experimental anti-superhuman chemical inside, the group decides to infiltrate the warehouse and destroy the chocolate before its distribution, though they have to fight against a giant security robot and a rival superhuman rock band...