Douma Daishi

An Outsider who washed up on the shores of Tenguu Island, the leader of the Yellow.
He is the guardian who took in little Olympia, who was left without parents.

The Yellow were granted the power to hear the voice of Hiruko and assist him.
Only the leader of the Yellow is allowed to hear Hiruko's voice.

He is Olympia's father. In "Catharsis" he is watching over the island's developments in order to pass on the leadership of the Yellow to the next generation.