Shimomura aiva chizvarwa cheKōchi Prefecture, uye akapedza kudzidza mukirasi yechi20 yeImperial Japanese Army Academy muna 1908. Vamwe vaaidzidza navo vaisanganisira Muchinda Asaka, Muchinda Higashikuni Naruhiko, Muchinda Kitashirakawa Naruhisa, Mitsuru Ushijima, Heitarō Kimura, Takashi Sakai, uye Shōjirō Iida. Akazopedza kudzidza mukirasi yechi28 yeArmy Staff College muna 1916. Mushure mekushandira munzvimbo dzinoverengeka dzevashandi uye manejimendi mukati meImperial Japanese Army General Staff, Shimomura akatumirwa kuFrance semushandi wemauto muna 1919. Akadzokera kuStrategy uye Kuronga Bureau yeGeneral Staff muna 1921. Akatora chikamu semumwe wevamiriri veJapan kumusangano weGeneva Naval kubva muna 1928 kusvika muna 1931. Kubva muna1919 kusvika muna 1935, aive mutungamiri we1st Heavy Artillery Regiment, Prince Kitashirakawa Naruhisa, Mitsuru Ushijima, Heitarō Kimura, Takashi Sakai, uye Shōjirō Iida.
Strategy and Planning bureau yeGeneral Staff