Shimomura bụ nwa afọ nke Kōchi Prefecture, na onye gụsịrị akwụkwọ na klas nke 20 nke Imperial Japanese Army Academy na 1908. Ndị klas ya gụnyere Prince Asaka, Prince Higashikuni Naruhiko, Prince Kitashirakawa Naruhisa, Mitsuru Ushijima, Heitarō Kimura, Takashi Sakai, na Shōjirō Iida. O mechara gụsịrị akwụkwọ na klas nke 28 nke Army Staff College na 1916. Mgbe ọ rụsịrị ọrụ na ọtụtụ ndị ọrụ na ndị ọrụ nchịkwa n'ime Imperial Japanese Army General Staff, e zigara Shimomura na France dị ka onye agha agha na 1919. Ọ laghachiri na Strategy na Planning Bureau nke General Staff na 1921. O sonyere dị ka akụkụ nke ndị nnọchianya Japan na Geneva Naval Conference negotiations site na 1928-1919 na 1931. Site na 1935-1930 ọ bụ onye isi nke 1st Army Army Artillery Regiment, Prince Kitashirakawa Naruhisa, Mitsuru Ushijima, Heitarō Kimura, Takashi Sakai, na Shōjirō Iida. A kpaliri ya na klas nke 28 nke Army Staff College na 1916.
Strategy and Planning bureau nke General Staff