Myu is a young dagon girl, a mermaid-like merfolk beastman, who originates from the ocean town of Erisen. She has long, wavy sky-blue hair and emerald-green eyes, with fin-shaped ears that distinguish her as a member of her tribe. Her life changes dramatically when she is kidnapped by slavers in the city of Fuhren due to the rarity of her species. She is rescued by Hajime Nagumo and Shea Haulia, and from that point on she becomes deeply attached to Hajime, initially calling him Onii-chan before settling on the term Papa. Myu is portrayed as an adorable and generally cheerful child, yet her kidnapping leaves her exposed to loneliness and danger. Following her rescue, she forges a strong paternal bond with Hajime, viewing him as a father figure. Her personality evolves as she spends more time with Hajime and his group; after arriving on Earth in later story events, she develops militaristic traits and enjoys giving orders in a drill sergeant-like manner, enthusiastically embracing Hajime's philosophy of showing no mercy to enemies. She is very eager to fight whenever confronted by an enemy. As a young child, Myu exhibits no notable combat abilities, but she possesses a unique supernatural charisma that allows her to attract and befriend mythical beings from a very young age. Her role in the story is primarily as a supporting character whose presence deepens Hajime's character, showcasing his protective instincts and providing a source of emotional grounding. Her development centers on shifting from a helpless victim into a confident and assertive girl who mirrors Hajime's pragmatic and ruthless outlook. Key relationships include Hajime as her adoptive father, Shea as one of her rescuers, and her biological mother Remia, whom she is eventually reunited with.