The calculated distance (air line) between Ōtsuki and Nishi-Tokyo-shi is approximately 33 miles respectively 52 kilometers.
By car or train, the actual journey to Nishi-Tokyo-shi is certainly longer, as only the direct route (as the crow flies) between Ōtsuki and Nishi-Tokyo-shi has been calculated here.
Air line (approximately)
52 kilometers
28 nautical miles