On April 15 of the same year, his type 6th submarine sank during the halfway submerging drill at the offshore of Shinminato, Yamaguchi Prefecture, and 14 officers on board, including the captain SAKUMA, died on duty.
4月15日、第六潜水艇は山口県新湊沖で半潜航訓練中に沈没、佐久間以下14名が殉職した。