Issen gorin which translated means "penny postcard" is a term associated with a value placed upon Japanese draftees in World War II. This term roughly meant that the individual was only worth the amount on the letter to draft them.
More specifically, "Issen Gorin" translates to "one sen, five rin", the cost of mailing a draft notice postcard (less than an American penny). The name Issen Gorin was the name Japanese Officers and powerful military personnel used to refer to the average Japanese soldier. Meaning that the individuals responsible for the wellbeing of the Japanese soldiers viewed the soldiers as being worth less than a penny. In their abusive training and continued treatment during World War II, the Japanese soldiers were constantly reminded by their superiors that they are nothing but worthless Issen Gorin.