Overview
- Emperor Naruhito inspected the Iwabuchi sluice gate and nearby flood-control sites on June 1, 2026, visiting the Arakawa Hydrology Museum and the MLIT Arakawa downstream river office before boarding a national disaster-response support boat to view the gate up close.
- Onboard the support boat he wore a life jacket, photographed facilities, listened to technical briefings, and asked officials about the size and equipment of the sluice gate.
- Reporters noted he examined both the newer Iwabuchi water gate and the older 1924 gate, which was replaced in 1982 and later designated a national important cultural property, and he viewed nearby water-level indicator pillars.
- Officials quoted by the press said the Emperor called the visit 'very educational' about disaster-prevention measures; the reports did not include any immediate policy announcements or government actions.
- The visit highlighted the engineering purpose of the Arakawa system—a roughly 500-meter diversion channel and sluice gates built to route excess water to Tokyo Bay—and is likely to raise public interest in flood preparedness and the condition of Tokyo's river infrastructure.