Brushing Up

 (じぶんみがき, Jibun Migaki) is an extra chapter included with Volume 2.

Summary
This story starts prior to the original storyline, when Saitama still had hair. Saitama has saved an old lady from a mysterious being, and is rewarded with a year worth supply of candy. Afterwards he thinks of how he has taken down over 10 mysterious beings since he became a hero for a hobby, and how he is not doing it for the gratitude but it does help him, and even how he has been pushing his body to the limits.

At his 300th day of training. Saitama starts to feel an unbearable stinging pain. As he does his daily jogging, he is shown to move at high speed, and thinks of how he is gradually getting used to the training, and how it even gave him a boost in his physical fitness, showing what he can do by saving a child from a speeding car, and crushing it's hood. disciplining the child about road safety, while people around are awing at his amazing feat. Continuing his thought of his growth, Saitama claims that he is able to move of how he thought superheroes would but there is still one flaw to his training, the stinging pain, which now comes at more often. A Mysterious Being then appears, boasting of how strong it is, and destroying a nearby vehicle, with rapid punches. Saitama approaches the being, but is unsure of his seccuss, because of the pain. The mysterious being is revealed to be the Tiger level monster Personification Of A Light Pull Cord, who talks of how he has changed and claims to be a "God" level threat. Personification Of A Light Pull Cord then complains about how unsatisfied he is attacking inanimate objects and wants to attack people. Personification Of A Light Pull Cord then notices Saitama coming from behind to attack him, and as Saitama is distracted by his stinging pain, Personification Of A Light Pull Cord punches him, knocking him through a truck and into a wall. Saitama then thinks he is at his limits, but then is determined to continue as he as not came so far for nothing. Then before Saitama is even capable of returning to the fight, Personification Of A Light Pull Cord attacks him with his - Pull Cord Rush. Saitama then appears to be down, and a tooth falls out of his mouth. Saitama then recuperates, much to Personification Of A Light Pull Cord's surpise. Feeling much better now that his decaying tooth is out (which was the origin of his stinging pain), Saitama beats Personafication Of A Light Pull Cord.

Back to the original storyline time. Saitama is seen leaving the bathroom, after seemingly brushing his teeth, and thinks of how maintaining healthy teeth prevents tooth decay.

Characters in order of appearance

 * 1) Himaaku (cover)
 * 2) Saitama
 * 3) Personification Of A Light Pull Cord