荒木貞夫
Matsui enrolled in the Central Military Preparatory School in 1893 and in 1896 was accepted into the Imperial Japanese Army Academy. Matsui was an excellent student and graduated second in his class in November, 1897. His classmates included the future generals Jinzaburō Masaki, Nobuyuki Abe, Shigeru Honjō, and Sadao Araki.