12 July 1947
(The West Australian, Perth, Australia)
Source: National Library of Australia, Canberra, ACT, Australia.
The whole article:
“ ‘Flying saucers’ have now appeared over Japan. The first flight was reported by a police officer at Kagoshima(Southern Kyushu) where the Allied invasion of Japan would have occurred in 1945 if the Japanese had not surrendered. The police officer, Shigeru Arrifuku, who made the report said that while on duty shortly after midnight on July 9 he saw some disk-shaped brilliant objects flying over Kagoshima Bayin a wave-like manner. The objects were flying north-east at a height of about 3,000ft.”
Satellite photo of Kagoshima, Japan(tageo.com)