Hai no Futago wa Shirokuro Tsukezu ni Sekai wo Sukuimasu.

14 years have passed since the "White Hero's" and the "Black Demon King's" decisive conflict during the "Black and White War". The world, now lacking of a Hero, was domineered by self-proclaimed "Heroes" who were showing off their power. However, some mysterious twins turn the tables around with their wisdom and ability...!

(Source: Kadokawa, translated)