 Next to be called up were the "kōbi" reserve who were to be either used to further fill in the ranks of line units or to be formed into new ones.The "hojū" reserve members were to be called up only in exceptional circumstances, and the territorial militia or national guard would only be called up in case of an immediate enemy attack on or invasion of Japan.The country was divided into six military districts, (headquarters Tokyo, Osaka, Nagoya, Sendai, Hiroshima and Kumamoto) with each being a recruitment area for a square infantry division consisting of two brigades of two regiments.