In the near future, in S City on 2047, Liu Xingyu, a vigorous girl who dreams of becoming an idol. Yi Ti, an alien girl was ordered to come to the earth to find the power of faith. Huai Si, an Ancient Princess who Accidentally came to the modern. And Anna Lina, a magical girl from the comic world across the dimension. The four people with each wish met in the audition of the new team of Project48 idols and were selected as preparatory students together. They became the “substitute substitute” of the sixteen selected idols on the stage and lived in the same bedroom.