Esra is the mother of Sinbad, the central protagonist of the series, and the wife of a former soldier named Badr. Her family resides in the Parthevia Empire, specifically in the small, impoverished village of Tison. Esra is a woman of short stature with long brown hair that she typically keeps tied in a braid. She has light brown eyes and thick eyebrows, and she commonly wears the standard clothing of her homeland along with hoop-shaped earrings.

In terms of personality, Esra is characterized by her deep kindness and her profound love for her family. She is a caring and intuitive individual who believes that her son possesses a special destiny or ability. Unlike some of the more insular members of her community, she is welcoming and accepting of strangers, as shown when she readily offers shelter to a mysterious traveler named Yunan. Despite her gentle nature, she is not without worry or frustration; she frequently frets over her husband Badr's carefree and passive attitude, as well as Sinbad's recklessness, and she advocates for her family's future with a practical sense of concern.

Esra is ailing for a significant portion of her son's early life. By the time Sinbad reaches the age of fourteen, her health is in a severe state of decline. Her illness causes her to lose weight and her hair to become disheveled, a stark contrast to her healthier appearance when Sinbad was young. Her primary motivation is the well-being and happiness of her son. She is acutely aware that her sickness has become a burden, tying Sinbad to their village and limiting his potential. In an act of selfless encouragement, she gives Sinbad his father's sword and urges him to pursue his own path, telling him to accomplish what only he can achieve. Her final wish is for her son to live a life of purpose, and she entreats Yunan to guide Sinbad after she is gone.

In the story, Esra is a foundational figure, primarily appearing in flashbacks and during the early narrative of Sinbad's childhood. Her death serves as a pivotal, formative tragedy for the young Sinbad. After Sinbad successfully conquers the dungeon Baal, he returns home two months later in real time to find his mother on the verge of death. In her final moments, she mistakes Sinbad for her late husband, Badr, and delivers her last words expressing her love and assurance that their son has grown into a capable and gentle man before she passes away.

Esra shares two central and defining relationships. Her relationship with her husband Badr is one of love mixed with frustration. While she loves him deeply, she is often exasperated by his unwillingness to fight against the societal discrimination they face as expatriots. She pushes him to take action to secure a better future for their family. Her relationship with Sinbad is the most significant, defined by mutual love and protection. She tries to hide the severity of her illness to avoid worrying him. Her dying words and her unwavering belief in his potential become a core part of Sinbad's motivation and drive to change the world.

While Esra does not possess any combat abilities or magical powers, her strength lies in her moral and emotional support. Her most notable ability is her profound intuition about her son's unique nature, correctly sensing that Sinbad is a special individual destined for great things. Her influence on the plot is entirely through her role as a mother, whose love and death catalyze Sinbad's journey. She appears later in the series as a brief vision or memory for Sinbad, appearing to him with his father's sword to reinforce her encouragement for him to pursue his destiny.