Psychopath Diary (2019)

The slow but intense description of the serial killer. Abrupt but sensualizing references of the serial killer. Not knowing whether to hate or love the killer trope.

Just like switch had a lot of comedic moments in it, Psychopath diary also had moments like this.
Both dramas are actually very thrilling, the FL and the ML actually had a lot of chemistry, this may be random or surprising but the ML also had quite a chemistry with the psychopath of the story.

Both of the main characters have lost their memory and find out to have a very dark past that they didn't know about. In Psychopath Diary, the main character finds out that he killed multiple people after reading a diary (which wasn't his, but he didn't know that), while in Forgotten the main character finds out that he had killed a family in the past, because the police officers and psychologists who live with him tell him.
Another similarity is that after losing their memories, both characters live in their old house in order to recall the memories that they lost.
Both of these characters end up confused, not knowing who they are, or who they used to be before their memory loss.

They might be not that similar in plot and story, but have a similar feel to them.
There are many crazy/funny moments in both on the one hand, and at times they get really dark and thrilling on the other hand.
In both dramas the main antagonist is a psychopath.
And in both there are some funny scenes with gangsters, who look tough at first, but turn out to be softies actually and respect the main characters (ML from PD, and FL from SWDBS), after they get beaten by them.

Even though the tone is very different the themes of both shows are similar plus the cat and mouse game with a serial killer very close to the male lead is the same.

They seem similar but both take a different path, although I don't know if she's innocent in lie after lie. It is still airing but hopefully its good.

Both stories revolve around a character who finds a notebook and comfortably uses it as their own. While Death Note delves into darker themes, both narratives share a comedic edge.

Both main characters experience personality shifts. From scaredy-cat, they become ruthless during times of need. They accidentally help people and deal with cool female police detective.

The comedy is also similar - slapstick, cruelty, and dark humor.

It feels like Bad and Crazy is also filled with cinematic references to other detective shows (and even western movies). Meanwhile, Psychopath Diary acknowledges the horror/thriller movie references, because the main character is an avid fan of those.

Yoon Shi Yoon, aka the master of double roles. In Train he plays 2 versions of the same detective with different personalities living in different worlds, while in Psychopath Diary, he plays the role of a timid office worker who believes he is a serial killer and has small bursts of moments where he "becomes" one.

Both shows also revolve around trying to find a serial killer. In Train the story focuses on finding who the killer is, while in Psychopath Diary the story reveals the killer in the first episode.

Psychopath Diary is more a comedic dark mystery, with moments that will make you laugh, while Train is more of a typical strict crime show. Both shows include crumbs of romance, but it is not the overarching focus.

They also both:
> Use dark comedy and push the absurd flawlessly within the plot.
> They embrace k-drama tropes, make fun of them yet simultaneously using them to further the plot.
> Have eccentric and unique Male Leads and quirky Female Leads.
> The Female Leads are active in the plot and strive to uncover mysteries. They are both skillfull and stubborn.
> The Leads establish a deep sense of friendship with a subtle hint of romance between them.
> The main antagonist is a serial killer, though in PD he's more prominent than in ZD.
> These two shows make for a light and entertaining watch.

Both shows have the questioning topic of "who is the real killer?"
Both shows have the Female lead starting off as trusting but slowly looses trust and becomes indecisive.
Both shows have the talk of Psychopathy but Voice 3 takes it into a darker point of view while Psychopath diary has a little comedy in it, which doesn't change the fact that the show is dark at sometimes too.
Psychopath diary can give you the same thrill as Voice for sure. In fact nearly every episode has a cliffhanger.
I recommended Voice 3 because it's the most darkest but to fully understand the story you need to watch Voice 2 as it is the baseline of the plot itself. A continuation basically.