Tokyo Valkyries a tactical card-based adventure featuring procedural generation, transports players to the streets of the Japanese capital, now gripped by a spatial anomaly. The ordinary lives of university students undergo a dramatic transformation after dark as they morph into guardians defending the metropolis against an invasion from a parallel dimension. To confront the Dark Queen Belzebia who has enslaved the fantasy kingdom of Grand Earth the protagonist, Haruka Fuchi, must forge an alliance with the mysterious Artesia. To save the universe from total annihilation, the allies must descend into the Abyss, where the source of a deadly corruption lies hidden.