Becoming a Knight from Slavery in Another World

A girl who was transported to another world was picked up by a slave merchant and put up for auction as a "rare and precious specimen." The one who bought her at the auction was a knight of the kingdom. The girl then conceals her gender and, as a way to repay the knight who bought her, begins working for the kingdom alongside the knight. However, her assigned post turns out to be a vacant position in a department known within the knighthood as a gathering of "crazy people."