Imperial Japanese Army Preparatory Officer School Site (Shinbudai)

The Imperial Japanese Army Preparatory Officer School (陸軍予科士官学校, Rikugun Yoka Shikan Gakkō) was the junior division of the Army Officer Academy system, responsible for training officer cadets prior to their advancement to the senior course at the main Army Academy at Zama (Sōbudai). The school's history is inextricable from the broader evolution of Japan's officer education system and its vast Asaka campus — named "Shinbudai" by Emperor Showa — remains one of the most significant surviving Imperial Army sites in the Tokyo metropolitan area.

The origins of the preparatory officer course date to 1920, when the Central Youth Military School (陸軍中央幼年学校) was reorganized as the preparatory division (予科) of the Imperial Japanese Army Academy (陸軍士官学校) at Ichigaya, Tokyo. For seventeen years the preparatory and main courses shared the Ichigaya campus, but as the Army expanded in the 1930s this arrangement became increasingly unwieldy. In 1937, when the main course relocated to Zama in Kanagawa Prefecture (receiving the imperial name "Sōbudai" / 相武台), the preparatory course was formally separated as an independent institution: the Army Preparatory Officer School, remaining at Ichigaya under its own commandant.

By 1940, with the China Incident escalating and war with the Western powers increasingly likely, the Army Ministry determined that the Ichigaya campus was inadequate for the expanded intake of cadets. In September 1940, the Ministry purchased approximately 210,000 tsubo (roughly 700,000 square meters / 173 acres) of land in Asaka, Saitama Prefecture — the grounds of the prestigious Tokyo Golf Club, established in 1914 — for 1.7 million yen. The construction project, codenamed "Yoshi Kōji" (ヨシ工事, from the school's abbreviation "予士"), was awarded to Takenaka Corporation and completed in an intensive 700-day construction timeline.

In the autumn of 1941 (on October 1, according to the Camp Asaka chronology), shortly before the attack on Pearl Harbor, the Preparatory Officer School completed its relocation from Ichigaya to the new Asaka campus. The vast facility featured barracks, classrooms, parade grounds, an athletics complex, a Shinto shrine (Otakebi Jinja / 雄健神社), and officer quarters set amid the rolling terrain of the former golf course. On December 9, 1943, Emperor Showa visited the school and personally bestowed the name "Shinbudai" (振武台), meaning "Invigorate Martial Spirit Plateau" — paralleling the "Sōbudai" designation he had given the main academy at Zama. A stone gate bearing the imperial calligraphy marked the main entrance.

The school's curriculum prepared cadets — typically aged 16 to 19, drawn from graduates of Army Youth Schools (陸軍幼年学校) or selected through competitive entrance examinations — for the two-year preparatory course before advancing to the senior course at Zama. Subjects included military tactics, weapons training, physical conditioning, mathematics, sciences, foreign languages, and the moral education expected of future Imperial Army officers. Notably, the school also accepted international cadets from allied and occupied nations, including China (Republic of China/Wang Jingwei regime), Thailand, Mongolia (Mengjiang), the Philippines, and India (Provisional Government of Free India), reflecting Japan's wartime co-prosperity sphere ambitions.

Between 1941 and the end of hostilities in August 1945, approximately 15,000 students passed through the Asaka campus. In April 1945, a B-29 bomber dropped a one-ton bomb on the school grounds, killing twelve people — a grim reminder that even training facilities deep in the Kanto plain were not immune to the intensifying strategic bombing campaign.

The school's final chapter was dramatic. Following Emperor Hirohito's surrender broadcast on August 15, 1945, a group of sixty-seven cadets under an officer's command refused to accept defeat. On August 24, they occupied NHK radio relay stations at Kawaguchi and Hatogaya in an attempted coup, seeking to broadcast anti-surrender messages to the nation. The attempt failed when the power supply was cut, and the cadets were disarmed — an echo of the larger Kyūjō Incident at the Imperial Palace on August 14-15. Sacred objects from the school's Otakebi Shrine were buried underground before the arrival of American occupation forces.

Following Japan's surrender, the United States Army requisitioned the Asaka campus as "Camp South Drake" (the northern section, Camp North Drake, lay across the Kawagoe Highway, also in Asaka). The 1st Cavalry Division established its headquarters here, and the camp remained in U.S. use until it was returned to Japan in stages, most of the southern area being handed back in 1973. The Japan Ground Self-Defense Force established JGSDF Camp Asaka (朝霞駐屯地) on the site in 1960. Today the garrison serves as the headquarters of the Eastern Army (東部方面総監部), the JGSDF's principal command for eastern Japan, and hosts multiple units and schools.

The Shinbudai Memorial Museum (振武臺記念館) stands within the garrison grounds, adjacent to the JGSDF Public Information Center ("Rikkun Land"). The museum building itself is not a surviving structure from the Preparatory Officer School; it is the former quarters for imperial family members (皇族舎) of the Army Academy at Zama (Sōbudai), which was dismantled, transported, and reassembled at Asaka in 1978 to serve as a memorial. Inside, the museum displays the school's nameplate and imperial chrysanthemum crest — both recovered from underground burial in 1965 — along with a 1/20-scale model of the Otakebi Shrine, uniforms, photographs, documents, and personal effects of cadets. The shrine's spiritual essence was formally transferred to Yasukuni Shrine in 1965.

Several wartime-era features survive on the garrison grounds: the former school headquarters building now serves as the Eastern Army Commander's office; a roundabout road layout from the wartime period remains intact; and a small artificial pond — originally the third short hole's water hazard of the Tokyo Golf Club — represents the sole physical relic of the pre-military golf course era.

Adjacent to the garrison lies the Asaka Training Area (朝霞訓練場), where the Asaka Shooting Range was constructed for the 1964 Tokyo Olympics to host pistol and rifle shooting events and the shooting component of the modern pentathlon. For the postponed 2020 Tokyo Olympics (held in 2021), a temporary Olympic-standard range was built on the same training area, so that the site has hosted shooting competitions at two Olympic Games. The shooting range's location on former Imperial Army training grounds represents a remarkably direct transformation from wartime military use to international sporting competition.