One day, the bright red sun stopped shining, causing the Breakdown Phenomenon—the destruction of Arata Kasuga's town and the disappearance of the people inhabiting it. All, however, is not yet lost; by utilizing the magical grimoire given to him by his childhood friend and cousin Hijiri Kasuga, Arata's world gets artificially reconstructed. In order to investigate the phenomenon, Lilith Asami appears before Arata, whose artificial world suddenly disintegrates. He is given two choices: hand over the book, or die. However, Arata chooses the third option—enrolling in the top-secret magic school Royal Biblia Academy, where six other magical users await him. Together with Lilith, these six form the Trinity Seven, the elite of the school who each bolster their own power and skill. With the ambition to save Hijiri and the help of his newfound friends, Arata stops at nothing to prevent the destruction of his beloved hometown and to bring his best friend back.

Unaired 13th episode. To thank the group for all their hard work in the past, Shirase invites the party to enjoy the sunny beach. While enjoying the wonderful weather and pristine waters, an accident causes Masato to lose all his memories, including those of Mamako! (Source: Funimation)

Forming a party with one's mother in an online game seems not only unlikely but also uncomfortable to most teenage gamers. Unfortunately, Masato Oosuki finds himself in that exact scenario. After completing a seemingly meaningless survey, he is thrown into the world of a fantasy MMORPG—and his mother Mamako actually tagged along with him! On top of all of that, Mamako turns out to be an overpowered swordswoman, possessing the power of two-hit multi-target attacks! After minor tension between the two, they search for party members, meeting the merchant Porta and the sage Wise, starting their journey to clear the game.