3 worlds: The real world, Cybertron and Sekai. The real world is set in Tokyo and Yokohama, and features Hatsune Miku and her friends. Sekai is a mystery world created from people's imagination.

Tsukasa Tenma, who dreams of becoming the world's best show star while working at a popular theme park. One day, Mafuyu goes missing, and the other characters find an Untitled song in her shared folder. When played, the song takes them to Sekai, where they meet Mafuyu, who also calls herself OWN.