Note: In some cases a character is portrayed by a different voice actor in the OVAs. These voice actors are also added. Main characters ; : : A 500-year-old immortal born in 1480, Yuta gained eternal life after consuming mermaid flesh along with fellow fishermen—an act that killed or deformed his companions while sparing him. After centuries of normal life, his immortality becomes apparent when his wife ages while he remains unchanged. Believing another mermaid could reverse his condition, he embarks on an endless quest. During his travels, he rescues fifteen-year-old Mana from mermaids who transformed her into an immortal for cannibalistic purposes. The kind-hearted Yuta develops numerous connections with others affected by mermaid flesh throughout his centuries of existence. ; : : Mana, born in 1965, becomes Yuta's immortal companion after he rescues her from a group of mermaids. Held captive since childhood, the mermaids granted her immortality at age fifteen intending to consume her for rejuvenation. She develops deep loyalty to Yuta, frequently saving him during their travels. Though harboring romantic feelings for him, her naive nature prevents full understanding of these emotions. Their bond grows as they journey together, with Mana's devotion remaining steadfast despite her childlike perception of relationships.
Other characters ; : An 800-year-old immortal with a child's appearance, centuries of isolation have twisted him into a merciless figure. His first act was to feed his dying biological mother mermaid flesh, transforming her into a Lost Soul. Having repeatedly lost adoptive parents throughout history, he now manipulates new caregivers by giving them small doses of mermaid flesh. During World War II, he stole a Nambu pistol and assumed the identity of Masato, a war widow whose own son and husband were killed during the war. When Misa's transformation fails, he tries to replace her with his young nanny, Yukie, who also becomes a Lost Soul. Following a confrontation with Yuta and Mana that ends in a fatal car crash, his body remains undiscovered. ; : : A war widow who lost her family during
World War II, she encounters the immortal Masato, who grants her longevity through mermaid flesh to serve as his mother figure. After eighty years of this forced relationship, her regenerative abilities weaken and Masato seeks a replacement. She ultimately perishes when attacked by Yukie, Masato's former nanny who had transformed into a Lost Soul. Her tragic story illustrates the destructive consequences of mermaid immortality, caught between an immortal child's emotional dependence and the flesh's inevitable deterioration. ; : : Yukie serves as Masato's devoted nanny, her nurturing nature making her an ideal candidate to replace Misa as his surrogate mother. Unaware of Masato's true nature, she consumes mermaid flesh at his urging but tragically transforms into a Lost Soul. Yuta intervenes and kills the monstrous Yukie, believing he is protecting both Masato and Misa from the threat she has become. Her transformation underscores the dangerous consequences of mermaid flesh consumption. ; : : Rin, the teenage daughter of Toba Island’s pirate leader, assumes command when her father falls ill. Seeking a mermaid’s cure, she encounters Yuta after he resurrects from a fatal sea battle. The two develop a romantic relationship, and Yuta pledges to remain on the island if he regains mortality. However, unwilling to subject another mortal to his immortal existence, he ultimately departs. Rin continues leading the island’s pirates, her story illustrating the painful divide between mortal and immortal lives. ; : : The wife of Sakagami Island's headman, Isago reveals the secret of mermaid immortality and urges her husband to seek one. Pregnant by her late husband (murdered by pirates three years prior), she requires mermaid flesh to ensure a healthy birth—being a land-dwelling mermaid herself. She explains to Rin that terrestrial mermaids consume aquatic mermaids, particularly during pregnancy. After obtaining the flesh, Isago returns to the sea, reverts to her true mermaid form, and successfully delivers twin merbabies. Her story exposes the complex hierarchy and reproductive biology of mermaids. ; : : Afflicted by a terminal childhood illness, Towa is cured when her twin sister Sawa administers mermaid blood—though this transforms her hair white and deforms one arm. Confined due to her disfigurement, she endures chronic pain until her fiancé, Dr. Shiina, begins transplanting arms from deceased girls, though each eventually degenerates. Following their father's death, freed Towa attempts to force mermaid flesh on Sawa as vengeance, but Sawa dies from a
heart attack before consuming it. Denied retribution, Towa commits suicide, demanding the destruction of Mermaid Hill and all its cursed relics. ; : : Sawa, Towa's identical twin, inherits guardianship of Mermaid Hill and its cache of mermaid flesh. Her desperate attempt to save Towa's life with mermaid blood results in her sister's disfigurement and imprisonment. After losing her husband in World War II and subsequently her child and father, the lonely Sawa guards the secret location until Towa threatens Mana's life. When Towa attempts to force mermaid flesh upon her as vengeance, Sawa unexpectedly succumbs to cardiac arrest before consuming it. Her death denies Towa retribution while underscoring the tragic consequences surrounding mermaid immortality. ; : : Shiina, Towa Kannagi's devoted fiancé, repeatedly implores her to abandon Mermaid Hill, but she consistently refuses. As a physician, he reluctantly performs gruesome arm transplants to alleviate her suffering from mermaid-induced deformities. He reveals to Yuta and Mana how Towa became consumed by her twin sister Sawa's existence. In the OVA, when Towa immolates herself in Mermaid Hill's flames, Shiina follows her to a fiery death, symbolically reclaiming their lost fifty-five years together. His tragic arc underscores the destructive power of mermaid-related obsessions. ; : : A desperate man consumes mermaid flesh from a beached corpse, seeking immortality. Upon awakening, he discovers his village destroyed and family slain, unaware he committed the atrocities himself. The incomplete transformation leaves him partially a Lost Soul—retaining speech and emotion but with grotesquely swollen eyes, earning the nickname "Big Eyes." While Mana pities his tragic state, Yuta and a local hunter are forced to kill him when his violent impulses persist. ; : : During the
Warring States period, a grieving father’s daughter, Natsume, is resurrected through an ancient
Buddhist ritual called "Hangon", which uses mermaid liver to grant immortality. Over time, the liver’s influence drives her to consume animal and human livers. Decades later, Yuta encounters Natsume and the monk who now seeks to kill her to end the curse. Though she wishes to join Yuta, her possessive father attacks him, allowing the monk to extract her liver. Natsume saves Yuta before her father leaps off a cliff with her. Mortally wounded, she briefly revives to bid Yuta farewell before reverting to skeletal remains. ; : : Yuta and Mana encounter Nanao, a wounded boy who escaped his kidnappers and miraculously heals after taking his "mother's" medicine. They return him home, only to discover his caretaker is actually his immortal grandmother, who—after consuming mermaid flesh 25 years earlier—kidnapped her own grandson to replace her now-grown son. When she attempts to feed Nanao mermaid flesh to make him immortal as well, Yuta intervenes. The revelation exposes the tragic consequences of mermaid immortality, as the grandmother's prolonged life drives her to unnatural acts of replacement and obsession. ; : : After being abandoned by her husband and son in 1969 due to deteriorating mental health, the woman consumes mermaid flesh, gaining immortality at the cost of severe facial scarring and chronic pain. Decades later, she kidnaps her adult son's infant child, naming him Nanao after her lost son. To conceal her disfigurement, she wears the preserved face of a deceased woman when appearing in public. When attempting to force mermaid flesh on her grandson to create another immortal companion, Yuta intervenes. Fleeing the confrontation, she perishes in a storehouse fire, ending her tragic pursuit of familial replacement through unnatural means. ; : : In the years preceding World War II, Nae befriends Yuta and reveals the secret of mermaid ashes brought by a nun to her village. She uses them to create the perpetual "red valley" flower field where their romance blossoms. Her jealous fiancé Eijiro murders her, then unsuccessfully attempts resurrection until later recovering the ashes. The revived Nae exists as a hollow shell until Yuta's return with Mana triggers fragmented memories. Eijiro fatally stabs her, and as the ashes' power fades, she dies again in the red valley. Her tragic story illustrates the imperfect nature of mermaid-based resurrection. ; : : Eijiro, an ambitious young man engaged to wealthy Nae Kogure before World War II, grows consumed by jealousy when she falls for the immortal Yuta. In a fit of rage, he murders Nae upon suspecting she plans to leave with Yuta. Obsessed for decades, he eventually revives her using mermaid ashes, though she retains no memories. When an aged Yuta returns decades later to find Nae unchanged, her fleeting recollections trigger Eijiro's enduring envy. He fatally stabs her, demonstrating how mermaid resurrection cannot restore what time and obsession have destroyed. His actions underscore the tragic consequences of attempting to circumvent natural mortality. ; : : A long time ago, Soukichi was an errand boy from Nae's family. Many years later after Nae's disappearance, as an old man, he helps Yuta and Mana, believing that Eijiro kidnapped her. ; : Akiko, the gentle sister of violent Shingo Kiryu, lives with lifelong guilt after accidentally blinding him during their childhood when attempting to stop his cruelty to animals. In desperation, she poisons them both with mermaid flesh - an act that leaves her in a comatose, doll-like state while granting Shingo immortality. He takes revenge by gouging out her eye. When Yuta ultimately confronts Shingo, he mercifully decapitates Akiko, ending her suspended animation. Her tragic story illustrates how mermaid immortality corrupts even familial bonds, transforming victims into permanent casualties of past trauma. ; : Shingo Kiryu, Akiko's violently deranged brother, displays sadistic tendencies while living at Kiryu Manor before the
Russo-Japanese War. After surviving Akiko's mermaid flesh poisoning attempt and his father's subsequent murder effort, he becomes immortal but is confined to the family basement. Upon release, he gouges out Akiko's eye in revenge. Each subsequent murder forces him to relive her final vision—his own monstrous visage attacking her. Believing her death will end these visions, he battles Yuta, who mercy-kills Akiko. When Yuta turns the blade on Shingo, the immortal realizes his eternal torment will persist and beheads himself in despair. ; : :Ayu is a girl in the mermaid village who took care of Mana. Ayu was next to sacrifice herself. Ayu is a mermaid, but died after spears pierced her body. Yuta found her body and showed it to the old women. ; :The flesh of mermaids is reported to give
eternal youth, regenerative self-healing properties, and
longevity. It is also a poison which can cause death, deformity or cause the person to become a Lost Soul or monster. Mermaids mostly live beneath the sea and have a normal lifespan. However, some live on land and are immortal, but they must sometimes eat the flesh of an immortal human to rejuvenate themselves. ==Media==