Iwata earned medalist honors after finishing at 5 under on the Amata Spring Country Club in Chonburi, Thailand.
The four, who came from a field of 75, will tee it up at Royal Liverpool starting July 17.
Ten players have qualified for the year's third major through the Open qualifying series.
The next event where players can earn their way into golf's oldest major will be the Mizuno Open, which will take place at JFE Setonaikai Golf Club in Japan in late May. The leading four players in that tournament who are not otherwise exempt will qualify for the Open Championship.