The calculated distance (air line) between Higashi-ōsaka and Ōtsu is approximately 28 miles respectively 45 kilometers.
By car or train, the actual journey to Ōtsu is certainly longer, as only the direct route (as the crow flies) between Higashi-ōsaka and Ōtsu has been calculated here.
Air line (approximately)
45 kilometers
24 nautical miles