National Route 251 is a national highway of Japan connecting Nagasaki, Nagasaki and Isahaya, Nagasaki in Japan, with a total length of 148.2 km.

Isahaya is a city located in Nagasaki Prefecture, Japan. As of June 1, 2024, the city had an estimated population of 131,467 in 55169 households, and a population density of 380 people per km2. The to