Gekitotsu no Hexennacht - Volume 4, Chapter 8: Wishes Gather

After Xia Feng transmigrated, his heart was mysteriously removed.In its place, a defective demon heart capable of sustaining life only for eighteen years was implanted.This is a magical heart that can sync with the power level of its target.To stay alive, he bound himself to the ultimate villain of the future, a Destructive Witch who was destined to destroy the world.The stronger the Destructive Witch becomes, the stronger he becomes!Thus, Xia Feng realized, it's not my fault for stirring up trouble: “Miss Witch, I admit you're strong, but not strong enough!”

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♪

In her last life, she was miserable and ordinary. This time, she got into the fashion and was reborn in another world. She was still the same person… even with the same body and face. What was the point of reincarnation? A childhood companion? He always pulled her hair and made troubles for her? A handsome boy? The boy never looked at her and was 15 years older than her! A prestigious teacher? The teacher spent his days eating and drinking, coaxed, played tricks, and controlled others… Too scary and better run away? No no no, such a challenging life was bound to be wonderful! Now let me take you back to the 70s and live a fast life!

- Description from Novelupdates

Akun, along with his classmates, was summoned as heroes by a goddess to save the world from the demon king. Akun, doubting he has what it takes to save the world, asks the goddess to send him back. Little did he know that this request infuriated the goddess. “How dare a mere mortal go against my will,” she thought to herself while maintaining her facade. She opens a portal for him to go back. Little did he know, the goddess had something else in store for him. As he passed through the portal, his soul was separated from his body, and he fell through the sky and earth until he landed in the body of an ant in the godforsaken forest. Left there to die by the hands of the goddess, Akun awakens the “Endless Evolution System.” [Ding!! The Endless Evolution System has been activated!! Grind to gain evolution points and evolve yourself and your comrades!!] “Endless Evolution System? Evolution points?” “Does this mean there’s more to my transformation? Can I evolve even as an ant?” [Ding!! Unique skill detected!! Skill: Super Gamer Shop!! Evolution points can also be used on this skill to buy items!!] Follow Akun on his new epic adventure, and find out exactly what awaits him, maybe some conquest and retribution.