Nierland—an A.I complex theme park where dreams, hopes, and science intermingle. Created as the first-ever autonomous humanoid A.I, Vivy acts as an A.I cast for the establishment. To fulfill her mission of making everyone happy through songs, she continues to take the stage and perform with all her heart. However, the theme park was still lacking in popularity. One day, an A.I named Matsumoto appears before Vivy and explains that he has travelled from 100 years into the future, with the mission to correct history with Vivy and prevent the war between A.I and humanity that is set to take place 100 years later. What sort of future will the encounter of two A.I with different missions redraw? This is the story of A.I destroying A.I. A.I diva Vivy's 100-year journey begins. (Source: MAL News)

As technology advanced, humanity gradually colonized the entire solar system, occupying planetary facilities from Mercury to Pluto. This results in a large-scale athletic tournament, the "Daiundoukai," where several aspiring female athletes from all around the solar system compete. The winner of the tournament is crowned the "Cosmo Beauty," obtaining a queenlike status. When outgoing potato farmer Kanata Akehoshi was a child, she witnessed a meteor-like object falling from the sky, crashing in a nearby forest. When she came to investigate the wreckage, she saw a damaged spaceship and a girl who seemed to have been in it weakened by the impact. The girl gave Kanata two wristbands, alongside a request that Kanata join the Daiundoukai and become the Cosmo Beauty. Kanata obliged, but before she could ask for the girl's name, she mysteriously disappeared—leaving nothing,not even the crater caused by the crash. Since then, Kanata has devoted herself to training, aiming to fulfill her promise. After winning the qualifying round to represent the planet Earth, Kanata goes to the University Satellite—an institution where she and other candidates study to prepare themselves for the upcoming competition. There, she meets and befriends her fellow competitors, helping them get along with each other to perform better in the games. As Kanata grows closer to the coveted title, so do her chances of meeting the girl who changed her fate—and she discovers an underlying mystery behind the Daiundoukai along the way.

The story follows Iruma Suzuki, a 14-year-old human boy, who is sold to a demon by his parents. The demon, known as Sullivan, takes Iruma to the Demon World and officially adopts him as his grandson. He enrolls Iruma in the Babyls School for Demons where he is the headmaster and where Iruma quickly befriends the demons Alice Asmodeus and Clara Valac. However, Sullivan tells Iruma to never reveal that he is human since he will be eaten if anyone finds out. Iruma then vows to blend in during his time in the demon world, although he only stands out because of all the situations and adventures that arise.

Shamisen is a traditional Japanese musical instrument that looks similar to a guitar. Teenager Sawamura Setsu's grandfather who raised him and his older brother Wakana, recently passed away. His grandfather was one of the greatest Shamisen players and the two siblings grew up listening to him play and learning to play the instrument. Since their grandfather's death, Setsu dropped out of high school, moved to Tokyo and has been drifting, not knowing what to do besides play his Shamisen. That's when his successful and rich mother, Umeko, storms into his life and tries to shape Setsu up. She enrolls him back into high school, but little does Setsu know that he is about to rediscover his passion for Shamisen. (Source: MU, edited)