The story of Princess Toyotomi revolves around a team of auditors who visits the beautiful city of Osaka and stumbles upon a secret, which has remained guarded from generations to generations by the citizens of the beautiful city for 400 years. The team has to discover financial irregularities if any and ensure the correct use of state funds by the Osaka government. In Karahori commercial district, the area with a long history they come across a strange restaurateur, his son who wants to be a girl and his sons friend. The auditors then inspect the H.R.H. Foundation, an organization set out to preserve Osakas historical castles. At first everything went smoothly but when Matsudaira revisits H.R.H. he discovers the building completely empty with no workers, desk drawers empty, and the phone lines disconnected. Confused enough he realizes that the whole city of Osaka is running a cover-up and now he tries to uncover the hidden story behind it.