Nightmare in Shizuoka: 15 Injured in Gas Mask Stabbing Spree at Yokohama Rubber Plant
By Lions Roar News Asia Desk
MISHIMA, JAPAN (December 28, 2025) – A terrifying scene unfolded at a tire manufacturing plant in central Japan on Friday afternoon, leaving 15 people hospitalized after a masked assailant launched a combined knife and chemical attack. The incident occurred at the Yokohama Rubber Co. factory in Mishima, Shizuoka Prefecture, approximately 100 kilometers southwest of Tokyo.
Authorities have arrested 38-year-old Masaki Oyama, a resident of Mishima and a former employee of the factory, on suspicion of attempted murder.
🎭 The Attack: Survival Knives and Gas Masks
At approximately 4:25 p.m. local time on December 26, emergency services received a frantic call from the factory reporting that “five or six people” had been stabbed and a mysterious liquid was being dispersed throughout the facility.
The Details of the Assault:
- The Attacker’s Gear: Witnesses described the suspect wearing what appeared to be a gas mask and wielding a large survival knife.
- Chemical Component: In addition to the stabbings, the attacker sprayed victims with an “unspecified liquid.” Preliminary reports from the Fujisan Nanto Fire Department suggest the substance was a bleach-like agent.
- Casualties: A total of 15 male employees, aged between their 20s and 50s, were rushed to the hospital.
- 8 victims suffered direct stab wounds.
- 7 victims were treated for chemical exposure to the liquid.
- 5 people are currently in serious condition, though officials confirm all victims remained conscious during transport.
🛑 Apprehension and Investigation
The suspect did not make it far. According to Shizuoka Prefectural Police, Oyama was heroically subdued and detained by factory workers on-site before officers arrived.
Investigative sources have revealed that Oyama was a former employee who previously lived in a nearby company dormitory. While he is currently unemployed, the presence of the gas mask and survival knife suggests a high degree of premeditation. Police are still investigating the specific motive behind the attack, looking into whether a workplace grievance sparked the violence.
🏭 Impact on Yokohama Rubber Co.
The Mishima plant, which employs nearly 1,000 people, specializes in the production of tires for passenger cars, trucks, and buses. Operations were halted immediately following the attack as forensic teams combed the “quiet” industrial area for evidence.
While Japan is globally recognized for its low violent crime rate and strict weapon laws, this incident follows a disturbing trend of “lone wolf” attacks in public spaces and workplaces over recent years.
