"Mieru Hito" is a supernatural mystery manga that revolves around the life of a young man named Yoshioka, who possesses the ability to see the "death lines" of people—visual indicators of their impending demise. These lines manifest as glowing threads that appear on individuals, and when Yoshioka touches them, he can foresee the circumstances of their death. This ability isolates him from others, as he struggles with the moral implications of knowing when and how people will die.

The narrative begins with Yoshioka leading a solitary life, avoiding close relationships to shield himself from the emotional burden of his gift. However, his life takes a turn when he encounters a mysterious girl named Aya, who also possesses a unique ability: she can see the "life lines" of people, which represent their vitality and potential for survival. Aya's presence introduces a dynamic contrast to Yoshioka's perspective, as her ability focuses on life rather than death. Together, they form an unlikely partnership, navigating a world where their powers intersect and influence the fates of those around them.

As the story progresses, Yoshioka and Aya encounter various individuals whose lives are intertwined with their abilities. They face moral dilemmas, such as whether to intervene in the fates they foresee or to let events unfold naturally. The manga explores themes of predestination, free will, and the ethical responsibilities that come with extraordinary powers. The relationship between Yoshioka and Aya evolves as they grapple with their own insecurities and the consequences of their actions, creating a compelling emotional core to the narrative.

The plot is driven by episodic encounters with different characters, each presenting unique challenges and insights into the nature of life and death. These encounters are woven into a larger narrative arc that delves into the origins of Yoshioka and Aya's abilities, as well as the mysterious forces that govern their world. The manga balances its supernatural elements with grounded character development, offering a thought-provoking exploration of human mortality and the connections that bind people together.