Overview
- Police identified the suspect as Masaki Koyama, 38, a former employee who was arrested at the scene after workers restrained him.
- Koyama was transferred on Dec. 28 to the Numazu branch of the Shizuoka District Public Prosecutors Office on suspicion of attempted murder.
- Fifteen male employees in their 20s to 50s were hospitalized, with at least eight wounded by a knife and several seriously injured but conscious at transport.
- Investigators say the assailant used a survival knife and sprayed a bleach‑like liquid while wearing a gas‑mask‑type item.
- The attack occurred around the day–night shift change, which police are examining as a possible targeted timing, and a knife believed to be used was recovered inside the plant.