Bierrez (or Viaresu) is a youkai who loosely follows Nadils army but keeps his loyalties to himself. He dislikes being told what to do and often creates his own schemes rather than following orders. Due to an encounter with the Dragon Lords blood as a young youkai, Bierrez was able to enter the Dragon Castle. While pretending to retrieve Cesia for Nadils army, he actually attacked the Dragon Castle single-handedly in order to rescue her (though she didn't know it and refused to leave). He has a close attachment to Cesia, having known her for several years and always watching out for her from behind the scenes. Although he appears to be trying to improve his own position, Bierrez puts a lot of effort into doing what he thinks is best for Cesia. In fact, he asked Rath to kill him in order to protect her. At the time of his "death" in the fourth volume, Bierrez possessed the Red Dragon Gem and was the Red Dragon Officer candidate.
When Rath "killed" him, he absorbed the Red Dragon Gem. When revived by Cesia in volume 21, Bierrez agreed to become the Red Dragon Officer. He now refers to himself as a Dragon rather than as a yokai. Also Fedeltas younger brother.