The ruler of the Western Seas, Yen took over the role from his father when he was just a young dragon. His fierce but just rule has expanded the Western territories two-fold since his father's day, and the Northern Seas are now effectively ruled by him as well. His military style is seen as ruthlessly efficient, and those that dare oppose his rule are mercilessly put down.

Yen was best friends with Seiryu, the crown prince of the Eastern Seas until Seiryu's father died. Now that the more kindly disposed Seiryu is the leader, Yen has been making moves towards the Eastern Sea territories as well. Yet, what should have been an easy conquest has taken three years, with Yen calling a retreat after each win, as if he just wanted to test his former friend.

While they look like mermen, these rulers of the seas are in fact dragons. Yen is the 'yellow' dragon type, hornless, battle-proud, and strong willed.