Masato, an immortal enduring eight centuries with the perpetual guise of a young boy, harbors a psyche fractured by isolation and twisted ethics. His endless existence fuels a desperate hunger for companionship, compelling him to orchestrate intricate deceptions. In post-war Tokyo, he preyed on Misa’s grief after she lost her family in World War II, posing as a helpless child before gifting her mermaid flesh to bind her as his immortal surrogate mother. Decades of suffocating dependence curdled into resentment, spurring Misa’s violent rebellion and igniting a relentless cycle of betrayal and retaliation.

To sustain his illusion of normalcy, Masato cycles through caretakers, tempting vulnerable women with mermaid flesh’s cursed promise. One recipient, Yukie, morphed into a feral Lost Soul, assaulting Misa and drawing Yuta and Mana into the fray. Unflinching in his cruelty, Masato targeted Mana, aiming to harness her immortality to replace Misa. His clash with Yuta unfolded through calculated traps and brutal combat, ending in a fiery car crash during his escape. Though his remains vanished, whispers of his survival linger.

Across eras, Masato’s guardians have perished—claimed by time, violence, or the flesh’s grotesque transformations. A stolen WWII Nambu pistol, kept as both relic and tool, mirrors his ruthless pragmatism. Behind his youthful facade lies a being stripped of empathy, prioritizing self-preservation over all else, even if it demands bloodshed.

His narrative weaves immortality’s corrosive legacy—a ceaseless dance of exploitation and abandonment. Where others, like Yuta and Mana, yearn to shed eternity’s burden, Masato embodies its darkest embrace: a solitary predator clinging to existence, forever echoing the tragedy of an unaging soul trapped in a world that withers around him.