My Vampire System (WN) - Chapter 19: Running out of time!

A great demon king who came from another world to conquer Earth. To save the Earth, Li Luyou could only first take care of this great demon king… a little girl proclaiming herself Her Imperial Princess.

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Author : Kinugasa ShougoIllustrator : TomoseshunsakuAs Ayanokouji and his classmates begin their second year at the Advanced Nurturing High School, they're greeted by a fresh gauntlet of exams and a fresh batch of rather unique first-year students. They'll have to get to know each other quickly, because the first special exam pairs the first-years with the second-years on a written test--with only the second-years facing expulsion if their team performs poorly! Worse yet? It seems one of the new first-years is also from the White Room. Can Ayanokouji avoid expulsion while sussing out the identity of this hidden foe?

Violet skies, a world undergoing massive changes, a deficient moon, interlinking voids…
When the world experienced a cataclysmic event,the majority of living things ceased to exist. Although humanity survived by hiding in the last safe zones, humans had to face mutated dire beasts and colossal source beasts that could break through the space barrier and enter the earth at any second.
Luo Yunyang, a young man who grew up in those calamitous times, obtained an attribute regulator and set out to walk the path of supremacy!

- Description from novelupdates