I really enjoyed how this fantasy drama was portrayed.
The emphasis on painting and the different styles and interpretations of how to depict a theme was very entertaining and educational.
The FL is caring for her artist father who has been driven mad. We later discover how and who was involved. Meanwhile his daughter is following in his footsteps. The back story of how she was blind and then became sighted is also part of the flashbacks that weaves together elements to bring us to the dramatic latter half.
The actors did a great job with special mention of the young actor playing the tiger demon. The ML, Ahn Hyo Seop, has different characters to play and is excellent in each.
As the blind scholar Ha, astrology advisor favored and funded by the king, he portrays a quiet dignity and elegance very appropriate to this role.
As the mysterious masked Ilwolseong he has built a network of spies and informants so is able to sell information to the wealthy.
As the Demon (Mawhang) and the use of CGI, he becomes a dangerously strong mythical creature.
The FL is a plucky character who is devoted to her father and desperately seeking a way to cure his mental illness. Her attraction to scholar Ha is very sweet and believable. She displays astounding ability to paint and to copy masters. This is her fate so that she can be chosen as the divine painter tasked with creating the portrait needed to use in a ritual to capture MaWhang the demon.

Visuals and attention to colour palette help to create the atmospheres of painting, love and crisis. The costumes and settings are done well and will be appreciated by anyone who enjoys costume dramas, The traditional Korean paintings a re a bonus.
If you are still hesitating about watching have a look at the extensive picture gallery.