Chagum's older brother (in the anime). Cares deeply for Chagum. When Chagum's belongings were ordered burned after Chagum was presumed dead, Sagum took over the task to protect Chagum's things.

Spoiler

He dies from overwork in his responsibilities as Crown Prince before being able to see Chagum alive again. In the book, there was no mention of him being close to Chagum, and he dies of illness.

(Source: Wikipedia)