One day, Reimu Hakurei is visiting Rinnosuke Morichika at his shop, Kourindo. He shows her one of his prized possessions, the golden sphere. However, when she touches it, it unleashes a mysterious beam of light. Rinnosuke starts acting strange, and a giant tower now stands where Kourindo used to be. The population of Gensokyo has also been replicated by clones who attack people on sight. As the Hakurei Shrine Maiden, it is Reimu’s duty to resolve this latest incident and bring peace back to Gensokyo.
Along the way, she is joined by Futo Mononobe, who has recently set out on a quest to become a first class sage. With her partner in tow, can Reimu make her way through the dungeons of the tower and put an end to this incident?