The Japanese 59th Army was formed on June 15, 1945, under the Japanese 15th Area Army as part of the last desperate defense effort by the Empire of Japan to deter possible landings of Allied forces in the San'yo region of western Honshū during Operation Downfall.

The Japanese 59th Army consisted mostly of poorly trained reservists, conscripted students and home guard militia.

Headquartered in Hiroshima, most of its command staff, including its commander Lieutenant General Yoji Fujii, were killed during the atomic bombing of Hiroshima.

Remnants of the 59th Army attempted to perform relief work and maintain public order in the devastated city with little success.

The IJA 59th Army was officially demobilized after the surrender of Japan on August 15, 1945.