Eris Boreas Greyrat is a noble girl and a tsundere with a short temper, known for her condescending attitude towards Rudeus when they first meet. Despite her violent tendencies, she has a shy side and is prone to hitting Rudeus for sudden physical contact. As she grows, she becomes more reserved and focused on her training, becoming known as the "Mad Dog" or Mad Sword King. She has long red hair with streaks of white, a nice figure, and swords around her waist on both sides.