The Hino Basic Shooting Range sits about seven kilometers east of JR Gifu Station, in a residential area that has grown up around it over more than a century. Established in 1907 as a firing range for the Imperial Japanese Army's 68th Infantry Regiment, it had been used by the Japan Ground Self-Defense Force since 1960. Originally an open-air facility, the range was converted to an indoor configuration in 2015 as residential neighborhoods expanded into the surrounding area and safety concerns mounted. On the morning of June 14, the final day of live-fire training for new cadets, exercises began around 9:00 a.m. Naoto Watanabe, an 18-year-old cadet who had enlisted in the JGSDF 35th Infantry Regiment at Moriyama Garrison just two months earlier in April, stood at the preparation line receiving live ammunition and loading it into magazines under instructor supervision. Without authorization, he suddenly chambered a round in his Type 89 5.56mm rifle. Sergeant Kosuke Yashiro, 25, who was managing the waiting area, noticed and ordered him to stop. At approximately 9:08 a.m., Watanabe opened fire.

Watanabe fired four rounds individually, not in automatic bursts. Sergeant Kosuke Yashiro was struck in the side. Master Sergeant Yasuchika Kikumatsu, 52, who managed ammunition distribution behind the firing positions, was hit twice in the chest. Sergeant Yusuke Hara took a bullet to his left thigh. Yashiro and Kikumatsu died from their wounds. Hara survived with serious injuries. All three victims were stationed at Moriyama Garrison. Watanabe later told investigators that Kikumatsu, the 52-year-old instructor, had been his intended target, though he never publicly explained why. He was subdued on scene and arrested on suspicion of attempted murder, with charges later upgraded to murder.

Japan's strict firearms regulations make civilian gun ownership nearly impossible, and military weapons incidents are vanishingly rare. The country's Firearm and Sword Possession Control Law imposes some of the world's strictest controls on private gun ownership, so violence involving firearms of any kind carries outsized weight in the national consciousness. Defense Minister Yasukazu Hamada issued a public apology and expressed condolences to the victims' families. International media, including the BBC, CNN, and Al Jazeera, covered the event extensively, underscoring how unusual such violence is in Japan. The Japan Ground Self-Defense Force immediately suspended all live-fire training exercises nationwide, a sweeping response that reflected both the gravity of the event and the institutional shock it produced. The incident drew comparisons to the 1984 JSDF Yamaguchi training ground shooting, one of the only prior comparable events in Japan's post-war military history. For a country that often processes fewer than ten annual gun deaths, two fatalities inside a military facility registered as a national crisis.

The legal process that followed reflected the complexity of Japanese juvenile and military law. Because the shooting occurred inside a Self-Defense Forces facility, the Gifu Prefectural Police and the military police force conducted a joint investigation. Watanabe was placed in psychiatric detention for evaluation from July to January. On January 23, 2024, prosecutors referred him to the Gifu Family Court on charges of robbery-homicide and attempted robbery-homicide, the robbery element relating to the unauthorized seizure of ammunition. On February 19, 2024, Judge Saori Hamaguchi ruled that the crime was brutal, showed no regard for human life, and carried serious social impact, ordering Watanabe remitted to criminal court for adult prosecution. The JGSDF had already dishonorably discharged him in September 2023. The range at Hino, which had witnessed over a century of military training beginning with the Imperial Army, would never operate quite the same way again.