Joining the navy on 16 December 1901, he passed out from the 32nd class of the Imperial Japanese Naval Academy on 14 November 1904, ranking 2nd out of 192 cadets.

After graduating from the 13th class of the Navy Staff College in 1914, he was promoted to lieutenant commander on December 1, and was assigned as a naval observer to the United Kingdom from 1917-1919.

In response, Nationalist forces moved into the Chinese suburb of Zhabei and skirmished with patrolling Japanese marines.

With his men giving way to the more numerous Chinese forces, Shiozawa ordered planes from his carriers to drop bombs over densely populated Zhabei.

The attack killed or injured thousands of civilians, and earned Japan the condemnation of the League of Nations.

In May 1943, following Admiral Isoroku Yamamoto's death in action, Shiozawa, a lifelong friend, presided over his state funeral.