4th Division (Osaka Division)

The 4th Division (第四師団, Dai-yon Shidan) originated as the Osaka Garrison, established in 1871, and was reorganized as a division on May 14, 1888 in Osaka. Its call sign was the "Yodo Division" (淀兵団), after the Yodo River. Known sardonically as the "Merchant Division" (商人師団, Shōnin Shidan), the division carried a lasting stigma within the IJA — other divisions joked that soldiers from Osaka's mercantile culture were more interested in profit than fighting. Whether this reputation was deserved is debated; the 4th Division fought at Nanshan, Liaoyang, the Shaho and Mukden in the Russo-Japanese War and served competently in China.

The divisional headquarters was located in an imposing Western-style building within the grounds of Osaka Castle, built in 1931 at the time of the castle's reconstruction. This building survives today as the former 4th Division HQ (旧第四師団司令部庁舎) and has been repurposed as a commercial facility (MIRAIZA Osaka-jo).

In 1937 the division was placed under the Kwantung Army and sent to Manchuria; it subsequently took part in operations in China through 1941, including the Battle of Changsha. In March 1942 it was assigned to the 14th Army and arrived in the Philippines on April 3, 1942, taking part in the final offensive on Bataan and the assault on Corregidor (May 5, 1942).

In September 1943 the division was reassigned to the 25th Army and moved to Padang, Sumatra, for garrison duty. It was later transferred to the 15th Army and ended the war with its headquarters at Lampang, Thailand. Its last elements were repatriated in June 1946.