In response to this issue, Tokugawa dug the Dosan moat stretching from the Ote-mon Gate of Edo Castle to Sumida-gawa (river), and initiated the reclamation of Hibiya inlet using the earth from the prior previous moat construction.
そこで徳川氏は、まず江戸城の大手門から隅田川まで道三堀を穿ち、そこから出た土で日比谷入江の埋め立てを開始した。