Naze Boku no Sekai wo Daremo Oboeteinai no ka? - Vol. 1 Ch. 2

[Kaarme]

Those two thought they saved a fellow human with their intervention, but in fact they saved the demon.

 

[SalvySaroj]

That's some chemical issue, you got there to mix "Reincarnation, Sci-fi, Time-travel, Post-apocalyptic too🤢"

 

[manohmaniamdone]

"Simplified Drake Bullet" alr man

 

[Pietje013]

Rewritten world, no parallel world.
Someone/ something changed the past, so he experience a different present.