She is a half-blooded deity from the continent of Derkarr who has been living in seclusion in the Misty Forest her whole life. Raised by her grandmother, Eirudy spends her time prior to the game creating dolls that she can control after feeding them Vitality. In an attempt to create a doll that can speak, Eirudy ends up encountering the human boy Adrian, which changes her life forever.
Like all deities, Eirudy has white hair and dark skin; however, unlike the deities of Vavelia, Eirudy has disguised her appearance with magic to have pale skin and to hide her long ears so she can blend in more with humans. Her eyes are red with dark pupils, showing her to be a half-blooded deity. Her red deity markings are along the sides of her eyes and can be easily mistaken as eyeshadow.
Her true appearance is seen in the main story at the end where she fell into the spring of Morell. During the post-game, it is revealed that she originally had dark skin and white pupils; as an artificial creation, she is a pure-blooded deity, but the magic used on her and her grandmother's claims made her believe she was half-blooded.
Having lived in seclusion, Eirudy's tone of voice tends to come across as apathetic and blunt. When she sees Adrian hauled off by guards, she mistakes him for a thief before finding out from Johannes that he is actually the son of Lord Regal.
True to her epithet, Eirudy's specialty is her dolls, which she can ride on in the field or summon in battle to aid her in combat. She possesses a Soul Stone that can collect Vitality from living enemies that she defeats or kills; that Vitality can then be used to awaken or upgrade her dolls, or to replenish her HP and MP in battle.
Along with magic, Eirudy also has powerful swordsmanship abilities, even moreso than Pieberry and Luna, the leads of the previous two games. She can combine her magic and swordsmanship for magical swordsmanship, which has greater reach than her regular swordsmanship and certain perks that aren't found with regular magic spells.
At the end of the game, it is revealed that Eirudy was created to be the replacement for two of Derkarr's deities; Revgato and Morell. The strongest power within her is Revgato's, who has the power of life; as a result, she is able to grant life by the end of the game.
- Out of four Witch Spring games, Eirudy is the only one whose game logo's stylized W is not based on her headgear; it is instead taken from her Soul Stone, which she wears around her neck.