The calculated distance (air line) between Ryūō and Higashi-ōsaka is approximately 178 miles respectively 287 kilometers.
By car or train, the actual journey to Higashi-ōsaka is certainly longer, as only the direct route (as the crow flies) between Ryūō and Higashi-ōsaka has been calculated here.
Air line (approximately)
287 kilometers
155 nautical miles