Exit east from the flying-location Lobelia Island. In Lobelia crossway cross the bridge beneath the houses, then go left (with an old guy in the grass). Finally cross another bridge west and the house is right there.
I have beaten the Pro Isle II in the Endless Isles, but after the Pro-Master bridge, the map just cuts off and there is nothing but a black wall. Has the game not been finished yet or have I bugged it somehow? Thanks