The calculated distance (air line) between Hamamatsu and Kozakai-chō is approximately 22 miles respectively 36 kilometers.
By car or train, the actual journey to Kozakai-chō is certainly longer, as only the direct route (as the crow flies) between Hamamatsu and Kozakai-chō has been calculated here.
Air line (approximately)
36 kilometers
19 nautical miles