The Genius Prince's Guide to Raising a Nation Out of Debt (Hey, How About Treason?), Vol. 4 (light novel)  (English, Paperback, Falmaro Toru)

To decide the successor of the throne, the three children of the imperial family must meet to talk through their options. Imperial Princess Lowellmina personally invites Prince Wein to join them in the city, which he successfully declines with dramatic flair. That's too bad, because now he has to deal with a whole new problem: His sister, Falanya, going in his stead! Worried sick, Wein sends Ninym after her, but nothing will soothe his anxious soul...other than going to the Empire himself!