After Being Reborn in the Apocalypse, My Nemesis Is Already My Ex-Boyfriend

If two people are such that one is the savior who rescues the world and the people in it, while the other is a demon king who kills without batting an eye and would destroy the world, could they ever be anything but mortal enemies?

As it turns out, yes.

The apocalypse caused by the spiritual qi revival arrived right on schedule. After being bitten by a spider whose fire powers had awakened once more, Ji Tingyue recovered his memories of his past life and realized something horrifying.

His ex-boyfriend, with whom he'd had a romance that had rocked the entire university, was actually Si Tianheng, his mortal enemy from his previous life!

Never mind that.

Since he'd been given another chance, he would save everything he could and nip every hidden danger in the bud. For example, Si Tianheng had caused all kinds of trouble in his past life. He couldn't let him run amok again this time.

Ji Tingyue quickly composed himself, picked up the only thing nearby that could be considered a weapon, a dagger, and set off to assassinate his ex.

Theme: Do your best, then leave the rest to fate.