Saitama only became a hero for fun, but after three years of special training, he finds that he can beat even the mightiest opponents with a single punch. Though he faces new enemies every day, it turns out being devastatingly powerful is actually kind of a bore. Can a hero be too strong?

[Source: AnimeLab]

While Saitama is training to become a hero, he needs one more thing before he can become a real hero. The origins of his hero suit is revealed.

Short episodes included with the Blu-ray/DVD volumes.

Saitama started out being a hero just for fun. After three years of “special” training, he became so powerful that he can defeat opponents with a single punch. Now, alongside Genos, his faithful cyborg disciple, Saitama is ready to begin his official duties as a professional hero working with the Hero Association.

However, the frequency of monster appearances is surging and it increasingly appears as if the Great Seer Madame Shibabawa’s prediction about the Earth’s doom is coming true. In the midst of this crisis, the “hero hunter” Garou makes his own appearance.

[Source: Crunchyroll]