土佐国
Born in Kōchi city Tosa Province (present day Kōchi Prefecture), Shimamura entered the 7th class of the Imperial Japanese Naval Academy following the Boshin War. Graduating at the top of his class of 30 cadets in 1880, he served as midshipman on the corvette , as ensign on the ironclad warship , and as a sub-lieutenant and lieutenant on the corvette .