Taisha Naval Air Base Ruins

Taisha Naval Air Base (大社基地, also known as Dai-ichi Shinkawa Base / 第一新川基地) was constructed from March to June 1945 on the dried riverbed of the Shinkawa River (新川), an Edo-period canal in what is now Hikawa-chō, Izumo City, Shimane Prefecture. The base was built through crash construction by the Navy's 338th Engineering Regiment dispatched from Maizuru Naval Station, supplemented by trainee pilots from Miho Naval Air Base in Yonago and large numbers of mobilised local people, including national-school children. The completion ceremony was held on June 8, 1945, and the facility was renamed from 'Shinkawa Air Base' to 'Taisha Base' in late June.

The main runway measured 1,700 meters long by 120 meters wide, with a 1,500m × 60m concrete-paved center section (10cm thick) flanked by 30-meter gravel shoulders. A secondary dispersal airfield, Naoe Base (直江基地), was constructed nearby in June 1945 with a 600m × 30m strip for special attack aircraft operations.

In early July 1945, the 762nd Naval Air Group headquarters and its 501st Attack Squadron relocated from Miyazaki Base to Taisha, bringing Yokosuka P1Y Ginga (Frances) twin-engine bombers. The unit conducted training and operational sorties until the war's end on August 15, 1945. According to surrender handover documents, the base inventory at war's end comprised: 30 Ginga Type 11 aircraft, 12 Ginga Type 16 aircraft, 1 Mitsubishi Ki-67 Hiryū (Peggy) army bomber, 1 Type 96 land-attack bomber, and components for 50 Yokosuka MXY-7 Ohka (Cherry Blossom) rocket-propelled suicide weapons stored unassembled. The base infrastructure included 22 large aircraft revetments (掩体壕/entaigō), 6 fuel storage tunnels, 7 torpedo storage tunnels (capacity: 72 torpedoes), and 3 bomb storage tunnels (capacity: 300 × 800kg bombs), along with barracks and operational facilities dispersed in mountain valleys east of the runway.

After the war, the runway area was used by the Japan Ground Self-Defense Force as the Shussai Training Ground (出西訓練場) before being progressively sold to private developers. In 2021, the main runway site was purchased by a private real estate developer, and by 2023 much of the concrete runway had been removed for residential construction despite active preservation campaigns by the 'Association to Consider the Future of Taisha Base' (大社基地の明日を考える会) and a Change.org petition seeking national historic site designation. As of the most recent surveys, Izumo City manages approximately 3,000 square meters of surviving structures — only 1.5% of the base's wartime footprint. The remaining runway segment (approximately 60m wide × 600m+ long) represents one of Japan's largest surviving wartime runway relics. Aircraft revetments and tunnel entrances remain visible in the hillsides flanking the former base area in Hikawa-chō.