Leviathan no Koibito
レヴィアタンの恋人
In 2077, much of the world is dominated by creatures resulting from mutated DNA. Some humans have also undergone mutations, gaining enhanced abilities. A young woman with notable strength, Kusaka Yuuki, defeats an immortal, unnamed male who is nearly invulnerable. After subduing him, she compels him to serve her as they seek a stable place to live.