noun
draft papers; call-up notice
Historically, the red paper used for military draft notices in Japan, especially during WWII. Often carries a strong cultural and emotional weight.
See also: 召集令状
戦時中、赤紙が届くと兵隊に行かなければならなかった。
During the war, when the red draft notice arrived, you had to go to the army.
noun
red paper
Original literal meaning; simply paper that is red in color. Less common in modern usage except in specific contexts like crafts or traditional items.
折り紙には赤紙や青紙など色々な色がある。
For origami, there are various colors like red paper and blue paper.