Naraijuku is located in Narai district of Shiojiri city in Nagano prefecture. It was a post town of Nakasendo which was one of the five routes; five highways leading from Edo, current Tokyo. Other famous post towns of Nakasendo are Magome and Tsumago.
Nakasendo was connecting Edo and Kyoto during Edo era. Edo was the biggest city in Japan, seat of the shogun and de facto capital of Japan. Then, Kyoto was the seat for the emperor and the official capital of Japan. Tokaido was also connecting Edo and Kyoto but it was running close to the Pacific ocean. On the other hand, Nakasendo was running through inland area.
There were 67 post towns of Nakasendo and Naraijuku was the 34th post town and it was the highest altitude of 11 post towns of Kisoji - a part of Nakasendo; around 900 meters above sea level. It is located along the Narai river and close to Torii pass which was the most difficult place to pass for travelers using Nakasendo. Therefore many travelers had to rest before and after passing the pass.
Naraijuku is also famous for lacquer and products made from lacquer are still sold around Naraijuku. Naraijuku can be reached by JR Chuo main line. Narai station is close to the historical area but please aware that limited express Shinano which connects Nagoya and Nagano regularly does not stop at Narai station. Therefore if you are traveling from Tokyo, please change at Shiojiri. From Nagoya(or Kyoto), change at Kiso-Fukushima.