Landlocked prefecture, Saitama is one of the prefectures in Japan which struggles to attract not only foreign tourists but domestic tourists too. Although it shares a boundary with Tokyo metropolis, and people from Tokyo can enjoy a day trip, Saitama has less tourists than other rival prefectures in Kanto region which Tokyo is located.
Yoshimi hundred caves is one of the few tourist destinations in Saitama prefecture. However, it is not well known to Japanese even the inhabitants of Saitama. It is located in northwest town called Yoshimi, which is also not well recognized among people of Saitama.
Anyway, Yoshimi hundred caves are worth place to visit if you are going to Kawagoe, definitely the top tourist destinations in Saitama. It is an archaeological site of cluster of cave type graves dug on a tuff cliff. It was designated as a National Historic Site in 1923. The Schistostega pennata, luminous moss growing at the site was also designated as a Natural Monument of Japan in 1928.
Actually the number of caves are not just hundred but at least two hundred. The caves were excavated in 1887 and it was not clear till then that the caves were built as for living or for as a graves. At the end of WWII, Nakajima Aircraft tried to build an underground aircraft engine factory and destroyed one tenth of the site. Luckily the war ended before the commence of the operation.
How to get here: Take either local bus from Konosu station on JR Takasaki line bound for Higashi-Matsuyama station or from Tobu Tojo line's Higashi-Matsuyama station to Konosu station. For Japan Rail Pass holder, it is better to get to Konosu taking Shonan-Shinjuku line from Shibuya or Shinjuku stations. However, if you are traveling from Kawagoe, take Tobu Tojo line to Higashi-Matsuyama.