Lake of Sorrows

Also known as Mizu-Umi no Fuko. It is the most immediate source of water near Kosaten Shiro. Peasants have a lot of superstitions around it. They believe it to hold the spirits of those who died at Beiden Pass and weren't buried properly.

The Lake of Sorrows is fed by the Three Sides River. (Secrets of the Crane, p. 26)