The great disease enemy, Kak'ke (beriberi) and the Imperial Japanese Army.

Although Japanese military officials had discovered that an improved diet could prevent beriberi by the late 19th century, their soldiers in the army suffered from beriberi during the Russo-Japanese War and World War II. A change in diet at the end of the Russo-Japanese War solved the problem and the army applied the lesson learned, along with postwar scientific discoveries about nutrition, toward the diet used during World War II. However, beriberi again plagued Japanese soldiers, this time due to poor logistics and unpalatable dietary supplements.