I recently finished the webtoon and spent way too long processing that ending. So the big resolution hinges on the protagonist, Yuna, finally rejecting the demon's terms outright after watching the cost spiral out of control for dozens of chapters. It isn't a triumphant victory where she gets to keep all the power and the happy life she bargained for. Instead, she uses the last shred of her agency to break the contract, knowing it'll revert everything—the success, the relationships built on supernatural influence, even some of her memories. The final panels show her waking up in her original, dingy apartment, back to her struggling life, but there's this quiet relief on her face.
What stuck with me is that the demon doesn't get punished or destroyed. It just... leaves, almost indifferent, ready for the next desperate soul. The real 'deal' was never really about outsmarting the devil; it was about Yuna realizing that a life built on a foundation of corrupted shortcuts wasn't a life she wanted to live, no matter how glittering the exterior. The ending is bittersweet and a bit hollow, which fits the story's tone perfectly. She's free, but she's also back at square one, just wiser and way more tired.