AmDevilCrafts

Ding!
[The Host has died!]
A system message popped up in front of Nell's body after his last dying breath.
Ding!
[Dark Evolution has been activated to absorb the death essence of the host.]
And then he opened his eyes to find himself in the past right before the battle started.
'Ah! Am I back to the past?'
Ding!
[Please choose a partner to start the Dark Evolution process.]
[Partner Condition: Must be a living creature from the Monster category, not the Human category]
[Partner Gender has to be Female.]
'Partner? A monster?'
Nell's heart pounded in his chest, and he felt a cold sweat coming on.
'A female monster?'

P.S. Cover isn't mine.

The System's Secret