"Duane Hodgkinson, now a flight instructor in Livingston, Montana, in 1944 was stationed near Finschhafen, in what was then called New Guinea. After he and his buddy walked into a clearing, they were amazed as a large creature flew up into the air. The men soon realized that it was no bird that started to circle the clearing. It had a tail "at least ten to fifteen feet long," (book Searching for Ropens, 2007) and a long appendage at the back of its head: apparently, a live pterosaur.
It is true that I found Duane Hodgkinson's testimony to be very convincing; he would have made a strong presence in court (I am a forensic videographer, having worked on many legal video projects with a number of attorneys, over the years).
Hodgkinson is one of many credible eyewitnesses who report similar characteristics of the flying creatures. Look into the U.S. Marine Eskin Kuhn; I interviewed him by telephone, early in 2010, and found his testimony to be highly credible as well. What many eyewitnesses report is a large featherless flying creature with a long tail. These features are common from those of many countries, cultures, and languages. That adds up to real creatures with features similar to those described. Very unlike any bird or any bat.
While yes, in 1944 New Guinea had been part of the "Greater Asian Prosperity Sphere", but is definitly not a Japanese Island, as you state in the title. Is is part of the Indonesian Island chain, with part of the flora and fauna being from the Australian continent ecosphere.