Akosode (小袖, lit., "small sleeves") is a type of short-sleeved, kimono-style garment that was traditionally worn in Japan until the latter years of the Edo period.
Originating in the Heian period as an undergarment for both men and women, the kosode was a plain white, often silk garment worn directly next to the skin. Both men and women layered, wrap-fronted, wide-sleeved robes on top of the kosode, with the style of layering worn by women of the Imperial Japanese court – known as jūnihitoe, literally "twelve layers" – featuring a greater number of robes than were seen on men. The kosode would also be worn as sleeping wear.
Following dress edicts designed to decrease the number of layered garments worn at court, the kosode gradually became outerwear from roughly the Kamakura period onwards. Styles of wearing the kosode – such as layering two kosode and wearing the uppermost robe stripped off from the shoulders – became popular, alongside the gradual development of kosode decoration techniques developing.
The kosode's proportions – a wide body and comparatively narrow sleeves – gradually evened out over time, before coming to resemble those of a modern kimono around the Edo period. The sleeves on some women's kosode also got longer and began to detach from the body below the shoulder, a style allowing the obi to become wider over time.
The parts of a kosode are roughly similar to those of a kimono, with the only major differences being the proportions of each aspect in comparison to those of a modern kimono.