I’ll get this short, overall, the story is not bad but not good either.
The mystery is crappy, this is more suitable to be a movie or mini-drama, instead of 16 episodes of drama with 1 hour 40 minutes duration each. It gives me zero of curiosity since from the first episode I can read the writer’s mind and all the bad guys are informed from episode 1.
Mintra herself (the female lead character), do nothing to uncover her beloved sister like friend unfair death, her "what so-called" investigation, leads her nowhere but more troubles and the ghost did her own revenge without none's help since she saw all people who responsible for her death. Since she's already known all the bad guys, I wonder why she's wasting her time.
I think if the writer hides them and uncovers all the bad guys one by one, as Mintra (the female lead) does her research, along with Ket ghost do her revenge, the mystery felling might stronger and might able to build up the viewer’s curiosity on the mystery. Or make simpler mystery like K-Drama Oh My Ghost, which has the same Romance-Horror genre, might be a good reference for the writer.

I can tolerate crappy writing, but what drives me crazy is the bad, bad, bad character creation! I will talk about the character, not the actor and actress.
First let me talk about Mintra, idk why the writer created a female lead that has an attitude and anger issue. I also don’t know why some writers try to picture a strong woman by creating the character always angry, screamer, and unimaginably rude. This Mintra character really triggered my psychopathy side, she is the first female protagonist lead character that shouldn’t deserve the title and turned me into a hater. Every time I watch her conversation scene with Kawin, I just want to strangle this annoying woman and chopped her into pieces!

Let me list down her disturbing behavior issues
This abnormal girl has some narcissistic issues. She is arrogance (rejecting any help though her sister health is on the line), lack of empathy (nonstop shaming and insulting Kawin of murder, to make it worse, she does it in public), NO remorse (after she's found-out that Kawin is innocent, she never ask him for forgiveness), acts without thinking, has no shame (car purchasing plot ( she turned down Kawin’s help… insult him, but dressed up for him… insult him, come again for the car… turned it down again… insult him again, OH MY DEAR DEAR LORD); and episode 4, robbery plot... why does she demand protection from "a murder suspect"?), distrusting, resentful, insecure, defensive, unforgiving, having internalized anger, and deceptive (she denied to might other possibility and insisted that Kawin is the murderer though there's NO EVIDENCE, but a simple meet-up appointment message). These are just a few of the character's behaviors, there are many more of her disturbing attitude that could make me write a full article for this character only. If she's real, I'll use her for my thesis material.
If I have to put reference for the writer, Han Seo Kyung from K-Drama "Train" will be a great example of a kick-ass character with resentment. The writer REALLY needs to LEARN how to write A LOT. I just hope the writer makes this character less hateful by making her know when to listen, when to SHUT UP, and more cool-headed.

And… after she’s nonstop shaming and insulting Kawin for the whole first 5 episodes, I can’t stand when she just stops at episode 6 after Ket gave her vision of Kawin’s innocence and found out that Kawin has been supporting her sister’s treatment. I want to slap her face when she’s smiling coquettishly to Kawin after she knows the truth… SHE DIDN’T EVEN ASK HIS FORGIVENESS!!! (My Dear God, have mercy on me for feeling this hate)
There will be no ends if I talk about this devilish wicked protagonist, the more I see her, the more I hate her. I better stop before my anger eating me alive.

Kawin himself is a weird character, the reason is… too nice (I mean too stupid) to be true. Opposite from Mintra, this character is unreasonably nice. What kind of a normal person that would support the family of an ex-girlfriend who admitted never loves him and even stole his money. Not to mention the family member accused him of murder without any evidence. Murder is a serious criminal act, no normal human being will calmly let an unknown person accused him of murder. I also find NO REASON for him to be in love with her... but he does. He just loves her... for an unknown mysterious reason... just because the writer creates him to.

I stop at episode 6 after the romance plot begins. I can’t stand watching Mintra’s shameless, no empathy, rude and ungrateful behavior towards Kawin..., as well as I can't stand seeing Kawin looked at the Bitch with a dazzled gaze as if she were a perfect angel