Reimu, as usual, misses the cleanup. There is an uncle who often visits such an abandoned Hakurei shrine... One day, when the uncle is visiting the shrine as usual to see Reimu... he hears a voice coming from somewhere.
It turns out to be the god Hakurei!
Reimu and her uncle are trapped in another world under the guise of Reimu training, and they must somehow find a way to escape.....