See also https://asiamedals.info/threads/1939-2nd-national-defense-physical-marine-training-tournament-badge-14.26108/
Reverse
國防體育海洋訓練大會 - National Defense Physical Education Marine Training Tournament
皇紀二五九八年 - Imperial Year 2598 = 1938
大阪毎日新聞社 - Osaka Mainichi Shimbun...
1938 japanese national defense badge
1938 national defense physical education badge
1938 national defense physical training badge
1938年防体育海洋訓練大会徽章
japanese badge
japanese naval badge
japanese navy badge
mainichi shimbun badge
national defense marine training tournament badge
昭和13年防体育海洋訓練大会徽章
防体育海洋訓練大会章