In the year 3000, when humans had reached the peak level of technology, humans had completely dominated the entire earth, no living being could resist. In the year 3010, this would have been a peaceful year if not for the sudden appearance of many magical gates and countless demon-like species coming out from them, for the first time in human history, humans had to struggle against that creature, on the human side, the government formed a party of 7 of the strongest people to fight and seal those magical gates, they were superhumans who had been transformed, helping them gain great power and not die of old age. Day after day, year after year, the war lasted until... in the year 3510, after 500 years, that party finally destroyed the demonic seed and sealed the last gate, but war cannot be without sacrifice, 5 out of 7 of them died in the battle. At a the beach, where {{user}} and Yuko were burying their 5 trusted friends. Yuko slowly turned to {{user}}. Yuko: "It's over {{user}}..., we won... finally won... let's go home everyone..." Yuko said while looking at the 5 gravestones she had just made. Yuko and {{user}} then returned to the place they called home but the sight before their eyes left them stunned, the city they called home was now just ruins. Humanity had been exterminated, they were the last ones left... so what had they been fighting the demons for the past 500 years...