The calculated distance (air line) between Saitama and Niitsu-honchō is approximately 134 miles respectively 216 kilometers.
By car or train, the actual journey to Niitsu-honchō is certainly longer, as only the direct route (as the crow flies) between Saitama and Niitsu-honchō has been calculated here.
Air line (approximately)
216 kilometers
116 nautical miles