https://warp.ndl.go.jp/ .. choose "English" from the top bar pulldown to view the website.

Sample URLS:

https://warp.ndl.go.jp/info:ndljp/pid/11986456/www.kesennuma.miyagi.jp/sec/s023/020/010/010/020/020/agenda2.20200603.pdf
https://warp.ndl.go.jp/info:ndljp/pid/11766846/www.kesennuma.miyagi.jp/sec/s023/020/010/010/020/20200721092320.html
https://warp.ndl.go.jp/collections/content/info:ndljp/pid/11986456/www.kesennuma.miyagi.jp/sec/s002/020/030/050/010/100/010/2020-01-28_zaisei.pdf

They don't have 14-digit timestamps. At a minimum they should be skipped.

The date is available by scraping the page for "collectDate". For example:

https://warp.ndl.go.jp/info:ndljp/pid/12767547/jweld.jp/

Contains the string;

<span class="warp_textArea_collectDate">2023?3?23?</span>

ie. March 23, 2023