Ichika is a high school musician who can enter a mysterious place called “SEKAI,” where she and her friends express their innermost emotions through music alongside Hatsune Miku. One day after giving a live performance, Ichika meets a new Miku that she has never seen before. No matter how hard this new Miku tries to sing, she struggles connecting with the hearts of her listeners. Miku must rely on the help of others to find a way to sing again.

Poppin'Party, Roselia, and RAISE A SUILEN's successful concert at the Budokan has passed. Kasumi and the others, who have left a lingering sound on the stage of their dreams, are approached by a mysterious woman. Their next stage is overseas?! Poppin'Party's music isn't stopping yet!

A story about three sisters struggling to survive in a desolate world surrounded by decaying buildings and red fog. The story revolves around Rin, a girl with an updo. There's also Ritsu, the big sister who has cat ears and is always calm, and Rina, the innocent, cheerful one dressed in a maid's costume. Just what is it that these sisters are after in this mysterious world?