Kirk here with my rather infrequent series on weed removal. Pulling out weeds is hard enough on flat surfaces. To remove the weeds that grow on the sides of a stone bridge such as Tsujunkyo you need rock climbers. And, I would imagine that an appropriate insurance policy would also be good to have.
https://news.yahoo.co.jp/articles/beb5b64112839f1e0057ed5779d9ee8155022a5f