The calculated distance (air line) between Kitakyushu and Ōnojō is approximately 31 miles respectively 49 kilometers.
By car or train, the actual journey to Ōnojō is certainly longer, as only the direct route (as the crow flies) between Kitakyushu and Ōnojō has been calculated here.
Air line (approximately)
49 kilometers
27 nautical miles