"Magi: Adventure of Sinbad" is a prequel to the main series "Magi: The Labyrinth of Magic," chronicling the early life and rise of Sinbad, a legendary figure in the world of "Magi." The story begins in the war-torn nation of Parthevia, where Sinbad is born into poverty. His father, Badr, a former soldier, is killed in a conflict with the neighboring nation of Reim, leaving Sinbad and his mother to struggle for survival. After his mother's death, Sinbad vows to change his fate and bring peace to the world, driven by a desire to end the cycle of war and suffering.

Sinbad's journey begins when he encounters a mysterious dungeon, a towering structure filled with traps, treasures, and a Djinn, a powerful spirit that grants immense power to those who conquer it. With the help of his childhood friend, Drakon, Sinbad successfully navigates the dungeon and forms a contract with the Djinn Baal, gaining the ability to wield lightning-based magic. This marks the beginning of his transformation from a destitute boy to a charismatic and ambitious leader.

As Sinbad grows older, he sets out to explore the world, seeking to unite nations and create a prosperous future. Along the way, he forms the trading company Sindria, which becomes the foundation for his eventual kingdom. Sinbad's charisma and strategic brilliance attract a loyal group of companions, including Ja'far, a former assassin who becomes his closest advisor, and Masrur, a Fanalis warrior with immense strength. Together, they navigate political intrigue, forge alliances, and confront powerful adversaries, including other dungeon conquerors and rival nations.

The narrative explores Sinbad's moral complexity as he balances his ideals with the harsh realities of leadership. His ambition to create a utopia often leads him to make difficult decisions, some of which have far-reaching consequences. The story also delves into the origins of key characters from the main "Magi" series, providing context for their relationships and motivations. Themes of friendship, ambition, and the cost of power are central to the narrative, as Sinbad's journey shapes him into the legendary king revered in the main series.

The manga concludes with Sinbad's establishment of the Kingdom of Sindria, a thriving nation that serves as a beacon of hope and prosperity. However, the story hints at the challenges and sacrifices that lie ahead, setting the stage for his eventual role in the larger "Magi" universe. "Magi: Adventure of Sinbad" offers a compelling exploration of Sinbad's character, blending action, adventure, and political drama to create a rich and engaging prequel.