Issued on June 1, 1942, under Japanese occupation in the autonomous puppet state of Mengkiang (Mengjiang), this mint never hinged stamp features a black overprint on an unissued 50-cent green Republic of China definitive. The original stamp depicts a military portrait, likely intended to represent revolutionary or nationalist figures. The overprint translates to a 25-cent denomination and signifies postal validity under the Mengkiang regime, which operated in Inner Mongolia during Japan's expansion in East Asia. Printed by gravure and measuring standard definitive size, this unwatermarked issue is catalogued under Michel JP-MG 84, Stanley Gibbons JP-MG 103, and CSS CN-IM MK178, but remains unlisted in Scott due to its provisional and regional nature. This example is well centered, with full gum, sharp print clarity, and no visible faults, making it a rare and desirable occupation-period specialty. Estimate "$180 – 220"