This is a fascinating and intricate tale of love, loss and obsession that spans 1500 years. The script very cleverly and effortlessly weaves its way from the past to the present and I found myself riveted by both worlds.

The man was once Do Ha (Kim Young Dae) an elite noble of the Silla Dynasty. His stepfather Lord Seo (Lee Kyung Young) hated him to his core. He had only one use for his son...in service fighting for the King. And because Do Ha served the King well, he brought Lord Seo glory and wealth. So Do Ha did as he was ordered without caring for his own life. Until he fell for her...the one woman he shouldn't have. Eventually their fated relationship was over as she chose to take revenge for the destruction of her family. So he wandered...neither resting nor forgetting..not even through eons of time. As a vengeful ghost ..he searched 19 lifetimes for her in the hope that he might return the favor. His only problem? He lacked a physical form. So when a top rated Korean celebrity named Han Jun Oh dies.... Do Ha...seizing his opportunity, takes over Han Jun Oh's form.
This is the chance that he has long been waiting for.

The focus of his obsession is Kang Young Hwa (Pyo Ye Jin) but she has no memory of him. She was once Han Ri Ta, a girl from a noble family in the Silla Dynasty. When her family was killed, she became the only survivor and she ends up as a maid in Do Ha's household. A maid that Lord Seo (his stepfather) takes an interest in and that connection between his father and Han Ri Ta the maid...resurfaces in the story of the modern day Kang Young Hwa. KYH is a heroic firefighter whose goal is to become the best firefighter in all of Korea and she is well on her way. Respected by her department and firefighter friends... she mostly dreams about traveling to the Antarctic. But ever so often, she has other dreams ...which are so real they blur the lines between her world and another and those dreams are getting harder and harder to ignore.
Thus these two are set on a collision course and I cannot wait to see where we go from here.

Although it is early in this series...we are sensing this one may be special. And if any of us ever thought that Kim Young Dae was just a pretty face..we have seriously undersold him. He is a very effective and mesmerizing actor. His eyes ...even when his face is solemn speak to a latent mix of powerful emotions, which we can sense and feel. Very difficult to do and amazing when it is done well. He portrays a man who on the one hand, knows he cannot ever atone for what he has done...but on the other...he cannot completely let her go. He pretends that only he is allowed to take her life...however, when the opportunity presents itself, he touches her hair gently instead.
So KYD is playing a very complex dual role and in my view, he is knocking it out of the park.

Likewise..... Pyo Ye Jin is exceptionally gifted ....I would watch her in any series she is in. She is persuasively believable. She is also rather unexpectedly beautiful. But her beauty does not overpower her presence. She is very fun to watch and I find myself smiling when she smiles. She is portrayed as someone who is preoccupied with doing her job well. She also has a strong sense of empathy, and a take charge, kick butt kind of mentality that drives her to take action to help others. That is why when Han Min Oh (On Joo Wan) Jun Ho's brother ...tells her that Jun Ho doesn't have long to live...and that someone is trying to kill him, her protective instincts kick in and she willingly decides to live with him.

So this is the setting for the story and since it promises to be anything but predictable, I encourage you to take a chance on it.
I think you will find it fascinating. I will be back to update as new eps are released...

@Final: Three reminders:
One: If you worry about the ending..don't. It was very satisfying.
Second: If you are afraid of the sadness, don't be. It was tempered by hope, and all of it together the sweet and the sad was very impactful.
Third: Don't stop short, this is a solid ten, perfect to the last second. So don't lose your nerve. Finish it and you will be so glad you did.

In conclusion:
The romance was unique and memorable. A lot of series..we watch and soon forget. This is one ....I won't forget. Not sure how it had so much depth with only 14 episodes, but somehow... they did it. Congrats to everyone involved with this project!
The cast did not disappoint, Kim Young Dae is more adept and versatile with every project. He will be a powerhouse someday..and Pyo Ye Jin is amazing in everything...and together...they rocked it! I felt a bit wishful at the end...wanting to see the young couple grow up together, but wow, what a lovely way to end it with hope.
And I loved the little nod to the title......Moon in the Day.. Enjoy my darlings....this is one to binge.

Happy Watching!