Tennen! Zetsumetsu Hero!!

An alien hero from another world travels to Earth with an army, expecting to battle the planet's legendary superheroes. Inspired by Earth's superhero television shows, such as Power Rangers and Ultraman, he prepares for an epic showdown. However, he soon discovers that Earth does not actually have any real superheroes. As his invasion begins, no one appears to stop him, leaving him confused and unsure of what to do with his powerful army in the absence of any opposition.