OVA
Description
Towa Kannagi belonged to a family secretly researching mermaids for generations at Mermaid Hill. A terminal childhood illness prompted her identical twin, Sawa, to administer mermaid blood, curing Towa but halting her external aging and causing severe deformities: her right arm mutated into a claw-like appendage resembling monstrous Lost Souls, and her hair turned white.
Declared dead and confined underground by their father to hide her condition, Towa endured decades of isolation. Only her fiancé, Dr. Shiina, visited, repeatedly offering escape, which she refused, stating she had "something to do." Chronic pain from her mutated arm led her to direct Dr. Shiina to amputate it and graft arms from recently deceased young women onto her body. These grafts deformed over several years, requiring repeated replacements.
After their father died, Sawa released Towa. By then, Sawa had married, had a child, and later lost her family, leaving the twins as each other's only relatives. Towa harbored deep resentment toward Sawa for living a full life while she suffered isolation, agony, and continued internal aging despite her youthful appearance. Towa's objective became forcing Sawa to reveal Mermaid Hill's location, where mermaid remains were kept, but Sawa refused.
Towa's pursuit escalated when Dr. Shiina brought Mana, an immortal girl, to the residence after a fatal accident. Intending to amputate Mana's arm for a graft, Towa was shocked when Mana revived. Yuta, another immortal, arrived searching for Mana. Towa unleashed a mutated dog (transformed by mermaid blood) to kill Yuta, though he revived later. Seizing the opportunity, Towa imprisoned Yuta and attempted to decapitate Mana to transplant her own head onto Mana's body, believing this would grant her a pain-free existence.
To save Mana, Sawa revealed Mermaid Hill's location. Towa took Mana there and threw her into a pit containing a live mermaid and a Lost Soul, demanding mermaid flesh in exchange. After Yuta intervened and killed the creature, Towa retrieved the flesh. She revealed her true motive: to force Sawa to eat it, ensuring her sister endured the same eternal torment. Sawa died of a heart attack before consuming it, robbing Towa of her vengeance. Devastated, Towa demanded the destruction of Mermaid Hill and all its artifacts. She then immolated herself in the ensuing fire, joining her sister in death.
In some adaptations, Towa's spirit later reincarnated as an immortal mermaid emerging from the sea. Her personality was defined by cold determination and a singular focus on vengeance, driving her to desecrate graves and mutilate corpses without remorse. Her physical appearance consistently featured bandages concealing her mutated arm, white hair, and the use of a cane for mobility.
Declared dead and confined underground by their father to hide her condition, Towa endured decades of isolation. Only her fiancé, Dr. Shiina, visited, repeatedly offering escape, which she refused, stating she had "something to do." Chronic pain from her mutated arm led her to direct Dr. Shiina to amputate it and graft arms from recently deceased young women onto her body. These grafts deformed over several years, requiring repeated replacements.
After their father died, Sawa released Towa. By then, Sawa had married, had a child, and later lost her family, leaving the twins as each other's only relatives. Towa harbored deep resentment toward Sawa for living a full life while she suffered isolation, agony, and continued internal aging despite her youthful appearance. Towa's objective became forcing Sawa to reveal Mermaid Hill's location, where mermaid remains were kept, but Sawa refused.
Towa's pursuit escalated when Dr. Shiina brought Mana, an immortal girl, to the residence after a fatal accident. Intending to amputate Mana's arm for a graft, Towa was shocked when Mana revived. Yuta, another immortal, arrived searching for Mana. Towa unleashed a mutated dog (transformed by mermaid blood) to kill Yuta, though he revived later. Seizing the opportunity, Towa imprisoned Yuta and attempted to decapitate Mana to transplant her own head onto Mana's body, believing this would grant her a pain-free existence.
To save Mana, Sawa revealed Mermaid Hill's location. Towa took Mana there and threw her into a pit containing a live mermaid and a Lost Soul, demanding mermaid flesh in exchange. After Yuta intervened and killed the creature, Towa retrieved the flesh. She revealed her true motive: to force Sawa to eat it, ensuring her sister endured the same eternal torment. Sawa died of a heart attack before consuming it, robbing Towa of her vengeance. Devastated, Towa demanded the destruction of Mermaid Hill and all its artifacts. She then immolated herself in the ensuing fire, joining her sister in death.
In some adaptations, Towa's spirit later reincarnated as an immortal mermaid emerging from the sea. Her personality was defined by cold determination and a singular focus on vengeance, driving her to desecrate graves and mutilate corpses without remorse. Her physical appearance consistently featured bandages concealing her mutated arm, white hair, and the use of a cane for mobility.