it's not an adaptation from webtoon, it's the opposite. it's adapted into webtoon so the webtoon itself still ongoing even have slower progress than the drama itself
But Guwon's deals last 10 years. It was Do-Hee's 11th birthday when they died. OH WAIT. Koreans count being born…
exactly! it was 10 years after Dohee's been born so that was the right time to end the contract. the question is why Guwon didn't recognize Madam Ju when he met her again?
I'm guessing that Dohee's parents made a deal with Guwon aka The Demon for granting their wish to have a kid and after 10 years Guwon come to end the contract and take their souls but Guwon and Madam Ju met after Guwon take their souls, that's why Madam Ju all of sudden go to church and confess her sin out of fear of meeting The Demon again. I don't know it's just my guess