Kumamoto is located in the center of the Kyushu island. It is ninety-five minutes away from Tokyo by airplane (1,072km), but is only eighty-five minutes from Seoul in Korea (631km). As the fifteenth largest prefecture in Japan, it covers approximately 7,402 square kilometers. The land mass is seven times that of Hong Kong and about half of Northern Ireland. Seventy percent of the land is forested. Gently rolling hills can be found in the north, while to the east and the south are mountainous areas that reach heights of 1,000 meters. Deep valleys are found in every area that afford views of breathtaking beauty. To the west is the Ariake and the Yatsushiro seas linked to the open sea, the East China Sea. Kumamoto has two national parks, one is the Aso Kuju National Park that includes the magnificent Aso volcano which boasts the best caldera in the world, and Unzen Amakusa National Park, the other, that comprise 120 islands, both large and small. In the geographical sense, Kumamoto has an abundance of beautiful landscapes.

The weather of Kumamoto is generally mild, and the Amakusa coastal area is the northernmost limit of a coral reef. The area around Kumamoto City has an inland climate, and is characterized by large fluctuations in temperature. In summer, it is not unusual to have a temperature above 35-C, and it stays hot through the midnight. On the other hand, in the middle of the winter, the temperature can fall below freezing. Local torrential downpours sometimes towards the end of the rainy season, owing to the terrestrial influences of hot and humid air currents from the southwest.

The population of Kumamoto, as of 1995, stood at approximately 1,860 thousand. This is an increase since 1972, but fifteen percent of the population is over sixty-five years old. This phenomenon of aging has begun ten years ahead of the rest of the country.