As a result of a field survey to collect specimens of Suzukielus sauteri, a sironid species endemic to Japan, for molecular and chromosomal study, we confirmed occurrence of the species from six different localities covering the Tokyo, Kanagawa, Yamanashi, and Shizuoka Prefectures. This includes the Yamabushi Pass, near Lake Yamanaka of Yamanashi Prefecture, which enabled us to conclude that the type locality of the species, which has remained ambiguous for a long time, is Lake Yamanaka. All the known records of the species are provided and mapped for the first time.