In the previous century, an unprecedented disaster known as the Invertia drastically reformed the world. The powers of existing nations declined significantly, paving the way for a conglomerate called the Integrated Empire Foundation to assume control. But more importantly, the Invertia led to the emergence of a new species of humans who are born with phenomenal physical capabilities—the Genestella. Its elite are hand-picked across the globe to attend the top six schools, and they duel amongst themselves in entertainment battles called Festas. Ayato Amagiri is a scholarship transfer student at the prestigious Seidoukan Academy, which has recently been suffering from declining performances. Through a series of events, he accidentally sees the popular Witch of Resplendent Flames, Julis-Alexia von Riessfeld, half-dressed! Enraged, Julis challenges him to a duel for intruding on her privacy. After said duel is voided by the student council president, Ayato reveals that he has no interest in Festas. Instead, he has enrolled in the academy to investigate the whereabouts of his missing elder sister. But when a more devious plot unravels, Ayato sets out to achieve victory, while being surrounded by some of the most talented Genestella on the planet. [Written by MAL Rewrite]

After his high school graduation, Yuuki Wakura realizes it has been five years since his sister's disappearance during a "Mato disaster." Throughout Japan, mysterious entrances have opened to a dimension called "Mato"—a demonic metropolis filled with disastrous monsters known as the "Shuuki" that threaten the safety of humans. However, a new hope arose, as the discovery of a Mato fruit that grants supernatural abilities exclusively to women allowed them to fight against the Shuuki. Due to this, a new matriarchal government was formed, establishing a female organization called the Anti-Demon Corps, which caused men to fall to the bottom of society. When Yuuki suddenly finds himself in Mato, he is unable to escape on his own. But just as he anticipates a gruesome end by the Shuuki, a girl in a militia outfit appears and protects him. As the chief of the Seventh Unit of the Anti-Demon Corps, Kyouka Uzen is ambitious yet devalued by her own peers due to her power being deemed unusual. Now in a life-or-death situation, Kyouka takes the opportunity to find out the true potential of her superpower by using Yuuki: in order to defeat the Shuuki, he has to become her slave.

After harboring an unrequited love for years, Naoya Mukai finally gets to date his childhood friend, Saki Saki. However, just as he tries to commit himself to this relationship, he receives an abrupt confession from Nagisa Minase. At first, Naoya tries to reject her but is soon overcome by feelings of not wanting to hurt Nagisa. Trying to avoid betraying his girlfriend's trust in him, Naoya thinks up a "solution" to make both girls happy—two-timing. Naturally, Saki rebuffs this idea, but through Naoya's and Nagisa's persistence, she reluctantly submits. With this, a three-way affair begins between Naoya, his girlfriend, and his "other" girlfriend, as they develop a relationship that deviates from the social norm.

After a fatal encounter with a truck, Takafumi Takaoka's uncle, Yousuke "Ojisan" Shibazaki, lies comatose for 17 years. When he finally regains consciousness, Ojisan begins to ramble in a foreign tongue and reveals that he had been transported to a magical world called Gran Bahamal. Takafumi dismisses his uncle's claims as nonsense until an incantation makes a cup of water hover in the air. In a flash of brilliance, the pair creates a YouTube channel to showcase Ojisan's magical abilities. The responsibility now falls on Takafumi's shoulders to acquaint Ojisan with everything that has transpired during his absence, including getting him up to speed with the internet, new technology, and surprisingly, the outcome of the '90s console war—the result of which was especially distressing for a hardcore SEGA fan. With Ojisan's wisdom from his other world experiences, they grow their YouTube channel and tackle online comments and trolls. The journey of this uncle-nephew duo promises to be anything but conventional.