MTL - Lord of the Myriad Demons - Chapter 881 heinous test

On a certain day, a certain thought came to Japan’s Sun Goddess. ——Aren’t there too many Japanese people being abducted to other worlds? It’s true that the large majority of Japanese are diligent and docile and soft-hearted, which makes them pretty much the best people to ask for favors. “But recently it’s just gotten way too out of hand…… Oh, I’ve got it! Whenever a Japanese person is summoned, I just have to summon an otherworlder!” And now, every time a Japanese person is summoned, princesses and elves and beastmen and whatnot are reverse-summoned. Under the acknowledgement of the government, they begin living in Japan. Today, too, Japan is at peace. And so begins this laidback isekai cultural exchange story♪

Based on the popular Vocaloid series, by HoneyWorks, called “Kokuhoku Yokou Renshuu (Confession Rehearsal)“:

Natsuki, a third-year at Sakuragaoka High School, who holds unrequited feelings for her childhood friend, Yuu, who’s in the Film Club. However, instead of being honest about her feelings, she makes him be her confession “rehearsal” partner. Unable to say her true feelings, things start to get complicated when Miou and Akari, who are also in the Art Club, get involved! Will she ever be able to confess for real!?

Teotihuacan, a sacred place of worship. In the vast world, feel the quaint and desolate ancient city, and the eagle cries and the leopard roars are chasing away.

Go back to Central America 700 years ago, when the Aztecs were very prosperous.

The priests stood at the top of the pyramid of the sun. One hundred thousand warriors covered the entire wilderness. fluttering. The high priest held his hands high, and the obsidian dagger gleamed in the sun, drawing a cruel and gorgeous arc, bringing the cycle of life back to the earth. Tens of thousands of cheers sounded, with the reverence of the ignorant era.

This was a gift dedicated to the sun god, in return for the sacrifice of the gods in creating the world.

Solemn sacrifices from sunrise to sunset, all-night revelry ignited the whole night, and so on for a hundred years, until white-skinned terrors came from the east coast, bringing blood, thunder, monsters, and disease.

Doomsday, as legend has it, or the end of the Fifth Era?

How can a traveler, in this fierce era, inherit the legacy of two thousand years of ancient Mesoamerican civilization, resist the invasion of Western colonizers with an immortal soul, and lead the ancient Aztec civilization to a new path ~~

- Description from novelbuddy

The world was once at war with 10 alternate worlds. This was known as the Concept War and our world won 60 years ago. All of this was concealed so no normal people are aware of this fact in the current time.

After the death of his grandfather, the high-school student Sayama Mikoto is suddenly summoned by the giant corporation IAI. He learns this world is headed for destruction due to the acceleration of the Minus Concepts. To prevent this, negotiations must be undertaken with the survivors of the other parallel worlds so their 10 concepts can be released.

And so Sayama is caught up in the final battle to clean up after the Concept War which left behind so much enmity.