Summer

 is an extra chapter included with Volume 3.

Summary
This story starts around Saitama's first year and a half of training. In Z-City, a crowd seen in Shelter No. 7 along with a small explanation of the Shelters, Disasters and Mysterious Beings, telling the readers that the Shelter's defenses have been activated and introducing them to the Mysterious Being - 170,000-Year Magicicada Nymph. 2 heroes are shown fighting the Magicicada Nymph, but with great difficulty as they are unable to harm it, and barely even hit it. Another hero then appears, with great confidence, claiming he shall defeat the monster, he is revealed to be Darkness Blade, a promising young rookie (at the time). Darkness Blade tries to be poetic, but as another hero states, it is better if he does not talk. With the introduction of those 3 heroes (At the time: B-Class Rank 61 - Darkness Blade, C-Class Rank 140 - Red Muffler, and C-Class Rank 299 Grad School Graduate) comes also the explanation of "pro-heroes", as how they are supposed to deal with the mysterious beings that appear, which they have failed to do. Coming into the shelter, beaten, the pro heroes are ridiculed by the citizens of said city, with Grad School Graduate even thinking of a quitting. Red Muffler claims the creature is unbeatable and suggest for everyone to just wait for it to die of old age, to which some citizens reply that it can take 170,000 years, while Grad School Graduate then also explains that while they were unable to defeat the monster, they did show some lost citizens the path to the shelter, to which those citizens are grateful, while some others are still bothered by the fact that while mysterious beings are appearing more often, so do weak heroes who come to fight them. Saitama is then shown, realizing he is in a shelter, instead of fighting the monster, which is why he even followed the heroes, while trying to leave, he is then noticed by a man, who thinks he has a death wish. The man and a few others try to stop Saitama from leaving the shelter, and one even pulls some of his hair out. The people then call the guards, and a staff member of the Hero Association tells him that he has no worry, and that he is safe, not permitting him to go out when he asks and continuing to ensure the citizens of their safety with a bullhorn, even claiming the Shelter to be "Perfect".

Saitama notices he has to use the toilet, but cannot find it do to the place being crowded, he then asks the female staff member of the location of said "Flawless" shelter's bathroom, to which she replies there is none, which Saitama states is a huge flaw. One hour later, Saitama is struggling with his filled bladder, thinking he might be ok if the monster outside is defeated in no more than 15 minutes. A random person on the phone, proceeds that the Mysterious Being threat level has risen to Demon, after defeating 2 A-Class heroes that came to beat it, and that they now must wait for the newly formed "subjugation squad", which will arrive in 3 hours. Hearing that, Saitama moves rashly, with people noticing him, claiming he is going to leave and moving to a nearby wall, claiming that the door seems more expensive to repair, thinking he cannot get out, some people suggest to just ignore him. Saitama then proceeds to punch a hole in said wall, while saying that he's going to the convenience store, much to the peoples surprise, who are not convinced he is the reason for the wall breaking and thinking he is dead for he went in the direction of the monster, but are also terrified for with the wall broken, the mysterious being may be able to enter. Saitama is then seen running to the convenience store, and is interrupted by the Magicicada Nymph, who is swiftly killed by the rushing Saitama.

At the present day, Saitama sees a 170,000-Year Magicicada Adult and notes the arrival of summer.

Characters in order of appearance

 * 1) Saitama (Cover)
 * 2) 170,000-Year Magicicada Nymph
 * 3) Grad School Graduate
 * 4) Red Muffler
 * 5) Darkness Blade
 * 6) 170,000-Year Magicicada Adult