Both center around crime investigative fathers who have strained relationships with their teen daughters. Working on cases that they soon discover their daughter is involved in, they work to hide certain details to protect them while simultaneously searching for the truth.

Gender swapped but very similar story for the most part- rich main character loses memory in an accident and starts to live with other main character while they recuperate (creating messes and causing trouble while doing so). Male leads are both harbouring secrets from the FLs, romcom atmosphere, etc..

Both follow an office-working female lead meeting and later convincing an everyday street-smart type of guy to have a fake relationship with her.

Both star Shin Min Ah, and involve a spontaneous/quick marriage at nearly the beginning of the show.

Door Lock as been a favourite of mine for many years. I'd say it's more of a subtle thriller, where as Don't Buy the Seller (or Target) is more action packed and in your face. I do prefer Door Lock but while watching DBTS I found I was never bored, and quite frankly it seemed like a faster paced version of Door Lock in many ways.

Groundhog day-type. Male leads have to relive the same day (the day their girlfriend dies) over and over after having mistreated her in a way, and desperately try to save her with these extra chances given.

Same circumstance for the male lead- gets into a car accident which leads to him losing his memories and reverting to his childlike self/mindset. Personally I prefer the overall storyline in Spring Day, as the character arcs and romance there were better executed (in my opinion).

Romance takes a backseat in both of these series, but not in an annoying or dull way. The main story and everything surrounding it is riveting, while the loveline helps ground our characters- stopping them from crossing over into insanity.

My Sweet Mobster leads first starred alongside eachother in Save me 2! Their relationship there was lovely, which is why I've been long anticipating their reunion here!

Both series focus on finding out what happened to deceased individuals. Move to Heaven takes a more sentimental approach, as they run a company that cleans out/takes care of the belongings. Unnatural is a bit more serious as it follows coroners and their discoveries. While different in occupation, I found both to be similar as they don't just simply solve the mystery of death, but more complex things going on in the person's life.

Both are about the female lead returning to their home town and ultimately finding love with a former classmate. Very heartwarming, simple, mature, and just plain beautiful love stories.

Under Your Bed takes a more-creepy-less-sweet approach to the very similar situation in 3 Iron, but is very good nonetheless.
While 3 Iron is near dialogueless Under Your Bed is a lot of narration with occasional interactions. I love both films despite shipping the leads in 3 Iron while standoffishly.. understanding(?) the leads in Under Your Bed. Under Your Bed is certainly a movie to watch and appreciate from a good film perspective, not one to go into expecting to be rooting for your lead character. As long as you can realize that a film can be about something bad without promoting said bad thing, I think you’ll enjoy it.