Sumireko Usami, psychic teenager and frequent visitor to Gensokyo, finds herself trapped in a nightmare wherein Gensokyo's residents are relentlessly attacking her with danmaku. A frustrated Sumireko decides to make the best of the situation by photographing the danmaku patterns to share on social media, and after doing so, finds that she's been freed from the dream. Three long weeks of danmaku nightmares follow...