Irukuku manifests as the human form of Sylphid, a female wind dragon bound as Tabitha's familiar. She adopts the role of Tabitha's younger sister in this guise, though her physical appearance suggests she looks older than Tabitha. Her personality remains cheerful, carefree, and playful, frequently expressed through boisterous behavior and minimal sense of shame. Maintaining this humanoid form demands considerable energy, imposing significant strain on Irukuku. Consequently, she rarely assumes it and lacks sufficient practice to convincingly mimic human behavior, resulting in actions and mannerisms that often appear distinctly non-human. Regardless of her form, she consistently addresses Tabitha with deep respect and affection using the term "onee-sama." Her true nature is that of the dragon Sylphid, contracted as Tabitha's familiar. While fundamentally sensible, she exhibits moments of childlike behavior.