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.

Veyron City—a mega-floating metropolis created from the discovery of new energy sources. Shuu, a young man who owns and operates a small business in the area, leads a meager life due to his reckless spending. Kisara, a girl who visits Shuu's office and home because she is constantly concerned about him. She works while attending high school in Veyron City, doing everything from clerical work to housework. Ayano, Shuu's ex-girlfriend and a senior colleague at the corporation he had previously worked for, is also worried about him. Thus begins the slapstick romantic comedy of three people in a slightly unusual relationship that takes place on an artificial island in the Pacific Ocean.

Alto Goldfilled, a diligent student at the Ortigia Academy of Magic, aspires to become a powerful sorcerer. But he is unable to become one as, despite his excellent grades and strong commitment to his studies, he fails his summoning class. With the threat of repeating a year hanging over his head, Alto tries following an old, worn-out grimoire in a desperate attempt to resolve his situation. To his surprise, he succeeds and summons a powerful demon named Vermeil. As a sign of gratitude for releasing her, Vermeil agrees to become Alto's familiar, sealing their relationship with a deep kiss. Little does Alto know what else he is capable of and what Vermeil's past hides.

After finishing their "debut," Kate, Emilico and three other pairs who started with them begin a new life as adults.