1921 (Taisho 10) On Monday, August 8, an explosion occurred at the army arsenal on Mt. Hiji in Hiroshima City. There were 7 deaths and 21 serious injuries. Four huge explosions spread fear in Hiroshima. The 5th Division (Commander: Lieutenant General Yamada Rikutsui) was dispatched to Vladivostok for the Siberia Expedition and returned to Hiroshima in August 1920, but its ammunition was not strictly controlled, for example, a safety needle was disconnected on the way back.
A report addressed to the Chief of Naval Operations (Shōichi Kanno), “Explosion Cause of Hiroshima Hijiyama Artillery”
It is presumed to be a defect in handling. The explosion was caused by the dropping of a howitzer housing for a gun or by giving a shock during transportation. The right grenade was from Vladivostok. It is suspected that some of them were not equipped with safety devices to prevent explosions. This cause was the same as the explosion in Shimonoseki last year. There were a lot of kinds of articles brought in this time, such as seized gunpowder and pyrotechnic articles, and high-heat medicine and pyrotechnic articles brought back from Vladivostok. Many of them were mixed with old things and treated roughly. In addition, it is considered that the search of the cause is complicated and very difficult, when unknown properties and components are mixed.