In a recent Suzunaan chapter, Reimu's storehouse turned out to have plenty of rice. This should have no bearing on the game - I think Reimu is the boss, because outwitting Reimu, the invincible protagonist, is a running theme in the spinoff games.
Some has also suggested that Reimu used her second and third spell cards when she realized Seija is creating gold, and tried to cash in herself. Makes sense given their names.