Specials included in the Blu-ray and DVD releases of One Punch Man.

One Punch Man 2nd Season's commemorative recap special.

Before Saitama became the man he is today, he trained and fought endlessly to become a hero. While every scuffle leaves his tracksuit uniform in tatters, he always has it mended for free thanks to his local tailor. One day, however, the tailor informs him that he must close up shop due to pressure from a local gang. Saitama decides to help him out—and gains something irreplaceable in the process.

The seemingly unimpressive Saitama has a rather unique hobby: being a hero. In order to pursue his childhood dream, Saitama relentlessly trained for three years, losing all of his hair in the process. Now, Saitama is so powerful, he can defeat any enemy with just one punch. However, having no one capable of matching his strength has led Saitama to an unexpected problem—he is no longer able to enjoy the thrill of battling and has become quite bored. One day, Saitama catches the attention of 19-year-old cyborg Genos, who witnesses his power and wishes to become Saitama's disciple. Genos proposes that the two join the Hero Association in order to become certified heroes that will be recognized for their positive contributions to society. Saitama, who is shocked that no one knows who he is, quickly agrees. Meeting new allies and taking on new foes, Saitama embarks on a new journey as a member of the Hero Association to experience the excitement of battle he once felt.