Maikomi-daira is a karst depression (polje) located in the southern part of Kurohime Mountain (1222m), which is composed of Aomi limestone. The area features developed karst topography such as dolines, ponors, and vertical caves. The surrounding limestone region has risen about 1000m, resulting in the formation of several hundred meters deep vertical caves with unique depths. Notable caves include Shirasono Cave (depth 513m, the deepest in Japan) and Senri Cave (depth 405m, second place), with the fourth deepest cave also located in Maikomi-daira. The water absorbed in Maikomi-daira is expelled again at the Fukurakuchi Cave, approximately 3.5km downstream, flowing into the Sea of Japan as the Tanigawa River. Between Maikomi-daira and Fukurakuchi Cave, the Tanigawa River flows underground and becomes a dry stream.

Being a heavy snowfall area, snow remains at the bottom of the doline, and the surroundings are enveloped in cool air even in summer, preserving an environment reminiscent of the Ice Age. A reverse phenomenon occurs where high-altitude plants appear as one descends towards the bottom of the doline, allowing for the observation of alpine plant communities at elevations around 2500m. Access to Maikomi-daira requires permission to enter.