"I've Seen It All" is a manga series that explores themes of existentialism, human connection, and the passage of time through a blend of surreal and grounded storytelling. The narrative centers on Akira, a young man who possesses the unique ability to perceive the entirety of a person's life—past, present, and future—with a single glance. This power, while seemingly advantageous, isolates Akira from others, as he struggles to reconcile the weight of knowing everyone's fate with his own desire for normalcy.

The story unfolds in a contemporary urban setting, where Akira works a mundane office job, attempting to blend into society despite his extraordinary ability. His life takes a turn when he encounters Rina, a free-spirited artist who remains an enigma to him. Unlike others, Rina's life appears fragmented and incomplete when Akira tries to perceive it, sparking his curiosity and drawing him closer to her. Their relationship becomes the focal point of the narrative, as Akira grapples with the ethical implications of his power and the emotional toll it exacts.

As the plot progresses, Akira's interactions with various individuals reveal the complexities of human existence. He witnesses moments of joy, despair, love, and loss, often unable to intervene or alter the course of events. This dynamic creates a tension between determinism and free will, as Akira questions whether his ability is a curse or a gift. The narrative delves into the lives of secondary characters, each serving as a microcosm of broader societal issues, from loneliness and regret to resilience and hope.

The manga's pacing is deliberate, allowing for introspection and character development. Akira's internal monologues provide insight into his struggles, while Rina's presence challenges his perceptions and offers a counterpoint to his detached worldview. The series balances its philosophical undertones with moments of levity and warmth, creating a nuanced portrayal of human relationships.

"I've Seen It All" concludes with an open-ended resolution, leaving room for interpretation regarding Akira's ultimate acceptance of his ability and his place in the world. The narrative emphasizes the importance of living in the present, despite the inevitability of knowing what lies ahead. Through its exploration of fate, connection, and the human condition, the series offers a thought-provoking and emotionally resonant experience.