Recommendations

The main guy character comes back home in order to find justice within the town from corruption. The town's corruption is found within every part of the town so he uses his reputation to find friends in the town who cannot stand the injustice of some of the posted government officials.

Both are about serial killings and suspense. Romance is the minor player in both. Tunnel is better because it balances well the suspense, the sad scenes and the comedy.

This is more like time travel, where a Joseon Dynasty scholar accidentally transports himself to 21st century into a movie set about Joseon Dynasty & falls in love . It can be considered both historical both modern and includes time travel

Both are similar plot lines of two best friends who went to the next level but couldn’t sustain their relationship beyond friends.

The story is relationship ups and down. I have a lover has darker, more mature take on relationship, but the angst and heart wrenching tale are similar.

The difference lies in the lead who in this drama actually fell for another girl.

Happy end guarantee.

The story include love story between two people, through ups and down, misunderstanding and love from both leads.

The couple has great chemistry and drawn the angst out of viewers.

I love it.

Happy-end included.

A lovely story, with angst, misunderstanding, and great love. Super enjoyable. Happy end is guarantee.

The male lead is super cute.

It has a story line where the male lead drives into the past and changes the timeline. There's an atonement component to this as well.

Both dramas deal with a mysterious storyline with a great ensemble cast and acting. The stories are top notch and effectively delve into various genres while settling with the main story idea. Writing is phenomenal and cinematography is somewhat similar because of the tones the two dramas carry. Actors really excel in their work and transport you to the scene of the situation.

If you enjoy lighthearted youth dramas, then you can't go wrong with these two. They're adapted from novels written by the same author. They both give you that fluffy feeling in your heart, but they do so without recycling the characters, which was something I was genuinely surprised by! Though you may have seen certain elements of these plots elsewhere, the dramas are executed in a truly unique and endearing way that you aren't reminded of the cliches.

Possessed is similar to The Ghost Detective its has those brutal killing, well the spirit and ghost not so much close but it has that in common and great actors with slight romance.

Not quite as epic as BOF, but if you enjoyed watching the normally arrogant and self-assured Joon Pyo become insecure and goofy as he tried to express his love, then you will like this one. The male lead has a similar vibe and you WILL laugh out loud watching him. Nice little love triangle and some good-looking guys round out the similarities.

Both dramas have obsessive male leads that show their love in a rather questionable, unhealthy manner. Still they are interesting and complex characters.
Female leads who are hurt and negatively affected by male lead actions.
In My Heart Twinkle Twinkle the male lead is given a chance at redemption.

Both couples knew each other and were dating in the past but they broke up for sad reasons and misunderstandings. After the break, they try to recover and continue on their own path.
They finally meet again after some years and finish to have to work together.
Both dramas will follow how they will face this situation. How they will deal with their past, will they be able to get over their painful separation and love each other.

Both are based off BL novels(forced into romancer in the series however). They both have mystery themes, and special forces to deal with crime. Guardian is more supernatural based however, but if you enjoyed one of these, you'll most likely enjoy the other.