"Head Start at Birth" centers on the life of Haruto Aizawa, a young man born into a world where individuals are granted unique abilities at birth, determined by a mysterious system known as the "Birthright Code." These abilities, or "Gifts," range from enhanced physical prowess to control over natural elements, shaping the societal hierarchy and defining one's role in life. Haruto, however, is born without a Gift, a rare anomaly that brands him as an outcast in a society that values these powers above all else.

The narrative begins with Haruto's struggle to navigate a world that dismisses him as powerless. Despite his lack of a Gift, he possesses an unwavering determination and sharp intellect, which he uses to challenge the status quo. His life takes a dramatic turn when he encounters a clandestine organization known as the "Null Syndicate," a group of individuals who, like him, were born without Gifts. The Syndicate operates in the shadows, seeking to dismantle the oppressive system that marginalizes them. Haruto is drawn into their mission, discovering that his lack of a Gift may be the key to unlocking a deeper truth about the Birthright Code and its origins.

As Haruto delves deeper into the Syndicate's activities, he uncovers a conspiracy involving the ruling elite, who manipulate the Birthright Code to maintain their power. Along the way, he forms alliances with key members of the Syndicate, including Rina Takahashi, a skilled strategist with a tragic past, and Kaito Nakamura, a former enforcer who defected from the elite's ranks. Together, they work to expose the corruption embedded within the system, facing formidable adversaries who wield extraordinary Gifts.

The series explores themes of identity, societal inequality, and the resilience of the human spirit. Haruto's journey is marked by intense battles, moral dilemmas, and moments of self-discovery as he grapples with his place in a world that has rejected him. The plot is driven by a balance of action, intrigue, and character development, with each episode revealing new layers of the complex world and its inhabitants. The story builds toward a climactic confrontation between Haruto and the architects of the Birthright Code, culminating in a resolution that challenges the very foundations of their society.