1. A vehicular navigation system comprising: a determination section that determines a difficult spot on a road based on at least one behavior of a behavior of a vehicle and a behavior of a driver of the vehicle, the difficult spot being a spot that hinders the driver from properly understanding a road structure or a course; and a supply section that, based on a raw image picked up at the difficult spot, supplies an image for providing assistance in driving at the difficult spot, the supply section including a creation section that creates a clean image by erasing at least partially a moving object that includes a pedestrian or another vehicle, from the raw image, the vehicular navigation system further comprising: a plurality of vehicle units disposed respectively in a plurality of vehicles; and a center unit communicably connected to the plurality of vehicle units, wherein: the vehicle unit includes a camera that supplies the raw image by picking up an image of an area in front of the vehicle where the vehicle unit is mounted, the determination section, and a transmission section that transmits the raw image to the center unit; the center unit includes a center reception section that receives the raw image transmitted from the transmission section the creation section, and a distribution section that distributes the clean image to the vehicle units; the vehicle unit further includes a vehicle reception section that receives the clean image distributed from the distribution section and stores the clean image in a storage unit, and a display section that causes a display to display the clean image stored in the storage unit when the difficult spot is encountered; and the supply section is implemented by the creation section, the distribution section, the vehicle reception section, and the display section.