Logline:
In a coastal city drowning in silence, high school diver Hasumi discovers she is the last descendant of an ancient pact—tasked with awakening the Deep Sea Sisters, three mermaid warriors who protect the abyss from a rising corruption known as the Black Tide.
Umiko isn’t a villain but a broken sister, and Hasumi’s true mission becomes one of healing, not destruction.
She followed the sound the way sailors follow stars. The compass shivered in her palm. Nights became maps of silvered foam and phosphorescent ink. On the third day, the waves opened like a secret and offered her a narrow passage lit by blue fire. There, waiting where water met something older than memory, were the Deep Sea Sisters. Mission Mermaiden - Hasumi and the Deep Sea Sis...
The Cartographer’s Hollow: The ocean’s maps were being eaten, routes forgotten, creatures misfiled. To right them, Hasumi would need to carry the compass into the hollow where lost charts were kept and relearn the naming of currents — a work of translation and humility that required accepting how little she knew.
Hasumi returned to the cliff town with salt still drying on her lips and a compass that now sometimes turned toward people rather than phantom places. She mended nets and taught children the songs of the wells. Sometimes, at night, she walked the headland and hummed the three-note call into the dark, listening for an answer that was no longer merely echo but conversation. Mission Mermaiden: Hasumi and the Deep Sea Sisters
Minegishi: A researcher at the rest area who acts as a "reliable older sister" figure, providing intelligence and logistics.
universe or fan-driven narratives) is a compelling reimagining of the classic “underwater rescue” trope. It blends tactical precision with the ethereal, often isolating atmosphere of the ocean’s midnight zone. At its core, the story follows Hasumi, a character typically defined by her towering presence and stoic discipline, as she is thrust into an environment where her usual strengths are tested by the crushing pressure of the deep. The Shift in Environment The compass shivered in her palm
The "Sisters" serve as both the goal and the primary mystery of the game. Each sister represents a different layer of the ocean—from the Twilight Zone down to the Hadal trenches.