Bad and Crazy (2021)

Both Bad and Crazy and The Journey Across the Night are mysteries with a comedic twist.
They share similar undertones as well, like bromance, serial killers, and mental illness.

Both MLs are detectives who work on a particular case and are relentless. Team dynamic and MLs both with great humor.

The starting of the drama is very similar as the ML in both dramas start off as a corrupt individual (works for money) and then are forced by circumstances (K in Bad and Crazy, parallel Universe in Welcome 2 Life) to fight against the bad guys who supported them.

And they both get assaulted by the FL in the first episode as soon as they are introduced.

It's not really similar in terms of plot, but it gives me the same vibes

The only similarity is corruption...

In both (movie & the series) the main characters are;

1. a police officer/detective
2. the 1st characters „helper that nobody can see“

Both also have: great action scenes with impressive fight-choreographies, a police case with a deep story and a lot of plot-twists, easy-going humor with a character that is the definition of a silly-goofy mood, great character development, a gril-boss character… I can be here forever tbh.

Bad and Crazy is simply Korean, less-gay, 10 hours longer version of this movie

Bothe dramas have one cop acting with a ghost in his head only or another personality acting on his behalf
both are packed with action thriller and funny scenes

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.

ML is crazy in both cases (or as irresponsible as they can come, in a police-type of drama). A lot of coincidental almost impossible things happen in order for the cases to be solved, but they do happen, and cases do get solved. TFR is more episodic than BAC, but there's a similar vibe to both of them.

Split personality is the theme
but in bad and crazy there are two actors playing the two personalities not just the same actors playing multiple personalities