Strange weather anomalies plague Gensokyo all at once: hail and rain fall on the Forest of Magic in summer, snow blankets Hakugyokurou, a dense haze smothers the Scarlet Devil Mansion, and an earthquake levels the Hakurei Shrine. Reimu and other protagonists set out to find the source. The answer lies with Tenshi Hinanawi, a celestial who finds her immortal life in Heaven monotonous and dull. Watching the youkai of Gensokyo stir up incidents from above, she grows envious and decides to instigate a catastrophe of her own—wielding the divine Sword of Hisou and her power to manipulate the earth itself.