"Summer" is an extra chapter included with Volume 3.
The story takes place during Saitama's first year and a half of training.
In Z-City, a crowd seen in Shelter Nr. 7 hiding from the mysterious being - 170,000-Year-Old Cicada Larva. C-Class Rank 140 Red Muffler, and C-Class Rank 299 Grad School Graduate are 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). Coming into the shelter, beaten, the pro heroes are ridiculed by the citizens, 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 became suicidal. 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 shouldn't worry, as he is safe, not permitting him to go out when he asks and continuing to ensure the citizens of their safety with a megaphone, even claiming the Shelter to be "Flawless".
Saitama notices he has to use the toilet, but cannot find it. 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, a 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 and proceeds to punch a hole in a wall, saying that he's going to the convenience store, much to the people's surprise. Saitama is then seen running towards 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-Old Cicada Adult and notes the arrival of summer.
Characters in Order of Appearance
- Saitama (Cover)
- 170,000-Year-Old Cicada Larva (Debut and Death)
- Grad School Graduate (Debut)
- Red Muffler (Debut)
- Darkness Blade (Debut)
- Shelter Nr. 7 Girl (Debut)
- 170,000-Year-Old Cicada Adult (Debut)