Raidorl Seiken Senki - Chapter 39: The Cursed Holy Sword

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.

This is a reincarnation/isekai story, about Matt (later TreeTree), an overpowered tree in a fantasy world that serves as the battlefield for an ongoing conflict between demons and the heroes summoned to oppose them.At first a bystander, over a long period of time, TreeTree will learn all sorts of skills, gain levels, and in doing so, build up a forest, train young subordinates, protect a village, and more.

Wang Yi gets a key, opening a door in 2022 will lead to 1982, and opening a door in 1982 will return to 2022.

Two very different great eras appeared before him:

Abundant dietary protection, developed industrial products, miraculous medicines, and explosive information, this is 2022.

Simple folk customs, rich wild resources, scattered antiques, and treasures of the age, this is 1982.

Traveling between these two eras, Wang Yi didn’t think much of it, he just wanted to live a good life.

- Description from novelbuddy