When the sky turns red, the moon turns black, and monsters begin roaming the streets, Satsuki Kakeru is at a loss for what to do. Along with his best friend Yuka, they try to decipher why they have been sent to this strange world, which is seemingly empty aside from themselves. However, when the Red Night ends, Kakeru and Yuka believe it was all a dream—until it happens again, and they are left in a dangerous situation. They meet four others in the same predicament: Kusakabe Misuzu, an expert swordswoman; Tachibana Kukuri, a strange mute girl who looks uncannily like Kakeru's deceased sister; Hirohara Yukiko, a lively young girl whose personality reverts to that of a cold killer when her glasses are removed; and Tajima Takahisa, a young pyrokineticist. As the six of them band together to survive and discover what this mysterious world is, things take a turn for the worse as six shadows appear before them...

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.

In the continent of Astraea, a man falls from the sky, possessing no memories other than his name, Yuuki. An elf named Kokkoro finds him, introducing herself as his guide in the world they are about to traverse. With Kokkoro's guidance, Yuuki is able to learn how this world works, from battling monsters to handling currency. To earn money for their journey, Yuuki and Kokkoro decide to go to a nearby guild association to accept a simple quest. In their expedition, they meet Pecorine, a somewhat gluttonous but charming girl skilled in battle. The next day, they also meet Karyl, a cat girl specializing in magic. After some time, a bond of friendship and camaraderie forms between them, and the four decide to create a guild of their own. As they continue their adventures, they explore the world, meet new people, and will perhaps uncover the mysteries behind Yuuki's missing memories.

Anzu Hoshino needs only three things in her life: video games, chocolate, and her beloved cat. Unlike other high school girls, Anzu has no time for or interest in romance. But as she begins playing a poorly programmed 3D otome game, a bizarre flying wizard named Riri emerges from the screen and calls Anzu subject one, the first person who will experience a dating game harem storyline in real life. Despite Anzu's fiery protests, Riri confiscates her favorite things to force her to focus on love. Riri orchestrates a series of unlucky incidents and romantic cliches that lead her to meet Tsukasa Kazuki, one of the most attractive boys in her school. Still enraged, Anzu is adamant about resisting Tsukasa's charm. As all the ridiculous fabricated scenarios help Anzu warm up to Tsukasa's pleasant nature, Riri throws other stereotypical pretty boys her way—and avoiding romance quickly becomes almost impossible.