The Nippon Maru was put into commission as an active-duty warship in the early Edo period, but it was remodeled into a smaller ship with 500 koku (139 cubic meters) in loading capacity and 60 oars, and again renamed "Dairyu Maru".
日本丸は江戸時代に入った後も現役の軍船として就役していたが、500石積み60挺立の船に縮小改造され、「大竜丸」と、改名を重ねる事になった。