The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.
The seawall program has no single completion date and remains partly unfinished as of 2026, so this pin is dated to the 11 March 2011 Tōhoku tsunami — the confirmed, exact date of the disaster that led Japan to commit to building it (construction of the network itself began in 2012, per contemporary sources).
Wikipedia's page on Japan's infrastructure ministry does not actually mention the Tohoku seawall program at all, focusing only on the ministry's organizational structure, so it offers only tangential institutional context rather than direct confirmation of the pin's claim.
Eco-Business's August 2026 report confirms Japan spent roughly $8.2 billion building 432 km of seawalls following the 2011 disaster, though it gives no specific completion date, supporting the pin's account without pinning down its own dated claim.
Something missing or wrong? Say it in your own words: a link that backs this pin up, a different start or end date and why, or a fact it lacks or gets wrong. The AI checks it against this pin's sources, searches for better ones, and adds any page that backs you up. The pin's own sources still count most.
East Japan Railway Company
