A demon from the underworld, possessed a human?!

Isabella Dunkeld, a villainess hated by her family and scorned by everyone—
Now possessed by Bella, the ruler of the demon realm and a demon herself.
‘How did I end up in this body?’
She has no memory of making a contract with the human Isabella, yet
when she comes to her senses, she finds herself trapped in Isabella’s body,
with all her powers sealed away.
For now, she decides to act like a “human.”

“So… how many people have I killed with these hands? Hundreds? Thousands?”
“Uh… you haven’t killed a single person, actually.”
“I haven’t killed a single human, yet they call me a villainess?”

For the demon Bella, humans are truly a mystery…