I, The Dragon Overlord - Chapter 560 - Father and Daughter

Qin Yichen returned to his youth with his memories of more than 10,000 years. Superb mental strength, advanced elixir formula, advanced martial arts.

- Description from xbiquge

Yun Bixue is in dire straits—

In the year 2220, a radiation source in the Pacific Ocean, tens of thousands of times stronger than a nuclear bomb has begun mutating exposed creatures into horrific monsters thousands of meters long. Mankind’s only hope was nuclear weapons, which only made matters worse. The combination of the natural radiation and nuclear radiation released an incurable and highly infectious virus, turning the 90% of the world’s population into violent zombies in mere weeks.

A continuation from where High School DxD Volume 25 left off.