1. A route calculation system, comprising: a display; a memory that stores a computer-executable route calculation program; and a processor that, when executing the stored program: sets a guide route from a departure location to a destination location; displays the set guide route on the display superimposed on a map image; receives an operation by a user designating a location on the displayed map image; acquires a road status of a road in the vicinity of the designated location; selects a pass-through road on the basis of the acquired road status, the pass-through road being a road by which the guide route will pass from the road in the vicinity of the designated location; and changes the set guide route to a route that leads from the departure location to the destination location by way of the selected pass-through road.