本作为百合向视觉系恋爱游戏，围绕着黑色海洋探索世界的秘密，出场人物均为女性
A sudden downpour shattered the planet’s tranquil routine. Twisted, monstrous fission creatures began to run rampant. Those who gained extraordinary powers to counter them were called: "Phelimatiya." Beneath the lighthouse stretched a mysterious black ocean, shimmering like polished ore. At its center stood an island-like sanctuary: [Black Reef.] Latitude 64°09' N, Longitude 21°56' W. Following the tides, they sought the rewritten truths of the world. "Welcome toour world."