This is an outer robe worn by boys of the royal household during Joseon dynasty until they celebrated their coming-of-age ceremonies. Its name, sagyusam, is derived from the shape of the robe whose sides and back have deep slits dividing the lower robe into four parts. Collar-trimming fabric bands face each other, and the robe is adjusted with buttons. In most cases, there were wide sleeves and deep slits in both sides and back. It was worn with the peaked cloth hat and braided-silk string belt. Boys from upper class families also wore this outer robe. This artifact is included in the List of Costumes for Special Occasionson December 1932, as one of the costumes prepared for celebrating the first birthday of Prince Gu.