Yuka, Rinko, Saki, and Natsumi are childhood friends and classmates nearing the end of their second year of middle school and eagerly awaiting their summer break. Unfortunately, it's a bittersweet time for this close-knit group, as Saki is transferring to another school. The girls are determined to keep the spirit of their friendship alive, even if only for this summer. They reminisce about a large stone the four of them used to visit, tucked away in an old Shinto shrine, and the belief that if four friends gathered around it and made a single wish, it would come true. Now, much to their surprise, they discover that old folktale is true. Natsu-iro Kiseki follows the magical events the girls go through during this last summer they’ll all spend together. As friendships get tested, and fantasies are fulfilled, the four classmates will end up learning a great deal about themselves and each other on the path to forging a summer that they’ll never forget.

The story revolves around Maya, the daughter of the former Headmaster of Waldstein Academy, and a time traveling agent Fumiaki Uchida. In the year 2012, the world had been invaded by aliens and time travelers were sent back to the year 1999 in order to find and destroy the Nostradamus Key, which Nostradamus Prophecy foretold as what would bring about the apocalypse. The series then turns to the year 1999, where Maya returns to the Academy with the intention of destroying the Academy by superseding her late father's position as the principal. Her plan was interrupted when she meets Fumiaki and learns of the forthcoming destruction. Despite being distrusting towards Fumiaki, they form a pact to look for the Nostradamus Key. In order to find the Nostradamus Key, time agents were provided with specially created cell phones. When a user finds an object of interest, by thinking of destroying it and taking a photo, and if the resulting image is that of a peaceful world, then the subject is the Nostradamus Key. Conversely, if the subject is not the Nostradamus Key, then the photo displays destruction. By using the phone, Maya and Fumiaki investigates occult occurrences as they occur in the town. (Source: Wikipedia)

12-year-old Oriko Seki, who lost her parents in a car accident, ended up living in her grandmother's Onsen Ryokan "Haru no Ya." With the ghost "Uribou" cohabitating with her and all the other odds, she ended up training to be a young female innkeeper. At first, she didn't like the training, but gradually felt her admiration for her title and began to train seriously. Thus, the growth of the young warrior Oriko begins. (Source: MAL News)

The seemingly ordinary and unimpressive Saitama has a rather unique hobby: being a hero. In order to pursue his childhood dream, he trained relentlessly for three years—and lost all of his hair in the process. Now, Saitama is incredibly powerful, so much so that no enemy is able to defeat him in battle. In fact, all it takes to defeat evildoers with just one punch has led to an unexpected problem—he is no longer able to enjoy the thrill of battling and has become quite bored. This all changes with the arrival of Genos, a 19-year-old cyborg, who wishes to be Saitama's disciple after seeing what he is capable of. 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, and Saitama, shocked that no one knows who he is, quickly agrees. And thus begins the story of One Punch Man, an action-comedy that follows an eccentric individual who longs to fight strong enemies that can hopefully give him the excitement he once felt and just maybe, he'll become popular in the process. [Written by MAL Rewrite]