Gekijouban Mononoke Karakasa summary:

Asa and Kame meet on their first day of serving in the Ooku - and quickly discover that things there are more complicated than they imagined. A strange cult, an unexplained delay in a palace festival, and even samurai in the Ooku are just some of the oddities they encounter. And what does the Medicine Seller, who peddles love potions and mononoke exorcisms, have to do with any of this...?