Sasaki, a 39-year-old corporate employee, has resigned himself to live a modest life without dreams and dangers. To his great surprise, his fate takes a brutal turn after he decides to adopt a Java sparrow that he names Pii-chan. The talking bird not only happens to be a reincarnation of a famous magician from another world, but it decides to grant some of its powers to Sasaki—along with the ability to traverse between worlds. Sasaki begins a lucrative business of selling technological items from his world to the less advanced civilization of the other. However, Sasaki's life becomes more chaotic when he stops an attempt on a woman's life with his new powers. Unfortunately, the woman Sasaki saved also happens to be a government agent named Hoshizaki, who is tasked with tracking down gifted individuals like him. Forced to join Hoshizaki's secret agency, Sasaki partakes in dangerous missions to find other gifted criminals. He does not even have the luxury of hiding in the other world, where a war is about to break out. If he wants to protect peace in both worlds, Sasaki will have to become the hero that no one expects him to be.

Princess Anisphia "Anis" Wynn Palletia has always dreamed of flying through the sky, even though the people of her kingdom consider it a silly ambition. Also at odds with her goal is the fact that Anis is incapable of using magic despite her noble status. Refusing to give up so easily, she renounces her right to the throne, and focuses on developing "magicology" by combining various resources with knowledge from her previous life on Earth. Due to Anis' nature, responsibility for the kingdom's future is passed onto her younger brother, Algard. Pushed into a political marriage with Euphyllia Magenta, a girl he hardly knows, Algard rebels by spending more time with a commoner girl than his fiancée. After Euphyllia tries to intervene, Algard publicly calls off their marriage and denounces his ex-fiancée as a bully. After crashing into the banquet where Algard makes the announcement, Anis rescues Euphyllia on the flying broom she is testing. She decides to make Euphyllia her assistant, which the other girl reluctantly agrees to. Although their partnership appears random at first, Anis has an ulterior motive for wanting Euphyllia's company.

Due to poor finances, an epidemic, and famine, the once prosperous Tearmoon Empire ultimately falls to a revolution instigated by its citizens and supported by neighboring nations. The rebellion also brings dire consequences for Mia Luna Tearmoon, the empire's extremely spoiled princess, who endures three years in the dungeons before facing execution. By some miracle, Mia finds herself reincarnated as her 12-year-old self, retaining full memories of everything that had transpired. With the pain of the guillotine blade freshly imprinted on her neck, Mia is determined to use this second chance at life to avoid the grim fate that awaits her. She utilizes all her knowledge to improve the state of the kingdom and gather personal allies, inadvertently winning over the people's hearts and becoming beloved as a saint.

Upon first seeing Earth from the Azatos Empire's survey ship, Chief Investigator Liza Luna plans to eradicate every lifeform on it immediately, leaving behind only useful resources. While surveying the planet, Liza discovers that human civilization has evolved at a pathetic rate compared to other lifeforms. Liza makes her way to the surface of the planet to properly inspect and understand its inhabitants. Still convinced that there is nothing beneficial to be found, the investigator makes her way into a cafe to gauge the planet's food culture. Liza walks into a cat cafe, where she meets creatures far cuter than anything else in the galaxy. Motivated by this new discovery, Liza decides to investigate Earth's numerous adorable inhabitants.