Vice Admiral Baron Yuzuru Hiraga (平賀 譲, Hiraga Yuzuru, March 8, 1878 – February 17, 1943) was a career naval officer in the Imperial Japanese Navy, Doctor of Engineering and head of the engineering school of Tokyo Imperial University and a leading Japanese naval architect in the 1910s and 1920s, responsible for designing a number of famous warships, many of which would later see action during World War II.

In 1916, Hiraga became chief engineering director for the Navy’s ambitious Eight-eight fleet project, and began work on a series of high speed battleships and cruisers.

The innovative designs for cruisers and destroyers formulated by Hiraga, which were extraordinarily powerful for their size, were among the most advanced in the world.

However, not content with these advancements, the Imperial Japanese Navy General Staff overruled Hiraga’s technical objections, and ordered that even more weaponry be added.

[4] In 1929, after Hiraga's design for the Kii-class battleship was shelved, he went into semi-retirement, and retired from active military service in 1930, becoming an advisor to Mitsubishi shipyards.

Resulting investigation revealed what a number of Western engineers had long suspected: Hiraga's designs were top-heavy and tended towards instability.

In 1939, he conducted what journalists later termed the "Hiraga Purge", by expelling most of the faculty of the university’s School of Economics, for publicly supporting liberal political doctrines.

He was posthumously awarded with the Grand Cordon of the Order of the Rising Sun and also with the kazoku peerage title of baron.