終わりのセラフ (Series) favorite_border

[DeepL Translation - needs review] Volume 1 Introduction: An unknown virus has destroyed the human race, leaving only children alive in an underground city ruled by vampires. Yuichiro Hyakuya, a stubborn boy, is the only one to succeed in escaping at the expense of his friends and vows to take revenge. What is the new world on earth that Yuichiro sees?

(Translator: DeepL)