Drama with sexual tension

Eternal Love of Dream - subtle and slow-burn.  Since its a Wuxia, it doesn't ever get above a certain level of explicit.  But the undercurrents are there, and the tension is there.  Probably the only thing I've seen Dilraba Dilmurat in where she had any chemistry with her ML whatsoever. Gao Wei Guang's spicy glances and stares carry this whole drama and make it light up.

Kakafukaka - absolutely terrible drama with some racy and scintillating scenes, you will feel guilty watching this one.  It's on the explicit side, as far as romances go.  It's one of those good-bad classics everyone has seen and no one wants to admit to.

Devil Beside You - old school but hot... strong sexual tension without anything too overtly explicit.  ML/FL seem perfect together with enough chemistry and suggestive dialogue to make your pulse race.

Lesson in Love - Although it has a  very understated aesthetic and atmosphere, the chemistry here is straight FIRE, and you will get a lot of kilig moments and several pretty scorching scenes..  I like how in the second half as the plot develops, the momentum of the passion between the ML and FL isn't lost and left to go flat.  Has a very "forbidden love"/taboo/angsty feel to it, the acting is incredible, and the ending is satisfying.

I Love My President Though He's a Psycho - An absolutely insane ride with a scorpio ML that has a look as hot as molten lava, some pretty feisty dialogue, and a few satisfying kiss scenes.  Srsly, get ready for a trip to crazy-town.  People who watch this tend to give it either a ten or a two.  So there ya go.  It's the ultimate good/bad drama.

The Rose - twisted and kinky and loaded with kilig moments and spicy dialogue.  And when I say twisted and kinky I am not messing around.  The ML and 2ML even incest-kiss at one point in there somewhere (even though this is not in any way a BL romance).  The 2ML cross-dresses.  And while there's no aaaaackshual incest consummated by the end of the drama, the FL/ML/2ML are all operating under the assumption that they're blood siblings.  But the ML and 2ML are H-O-T, and some of the situations and dialogue are so hot they'll melt you right down to the ground.

The Smile Has Left Your Eyes - intense and angsty, and there's even a fiery bed-related scene.  In Seo Guk has this dark smoldering way of looking at the FL that's just devastating.

That Winter The Wind Blows - less spicy and more understated, but still has some pretty hot moments.  The ML is the same ML from A Frozen Flower, and he just burns down the screen to the point that even the smallest of gestures between them becomes super kilig.

Nevertheless - wall-to-wall low-grade sexual tension, with a few pretty hot and spicy moments sprinkled in.  This one is pretty racy for conventional k-drama romances.  The ML/FL don't have the kind of epic chemistry as some others, but it's plenty good enough, they do have a few magic moments that leave you pretty fluttery.

Till the End of the Moon - Wuxia, and therefore no real explicit spice... but the chemistry is there and some of the scenes are absolute epic scorchers.  The ML is so hot in that dark-eyed way that it makes you want to scream and run around the block. Ont top of that, the show's aesthetic is sexy as well.  As long as you can tolerate the FL, I think it's worth the watch.

Que Sera Sera - Not exactly a super-spicy drama... kind of oldschool with strong makjang overtones and a plot that can get a bit tedious.  But this has one of the hottest kiss scenes I've EVER seen, Eric Mun is just straight fire, and there are some pretty sexy scenes in a more subtle and understated way.  (Now some people will recc 'Another Miss Oh' as sexy, and that's also Eric Mun.  I didn't find it sexy the way the FL in that one is constantly being humiliated and embarrassed.  But it just goes to show that Eric Mun can bring the heat -- although he's been cast in several dramas that don't take advantage of that whatsoever and really restrain him and dial him back)

Love is Phantom - Strange and spicy.  This one is a very simplistic, pared down J-drama.  It almost descends to that level of hokey and dumb that some of the racier J-dramas do.  But this one was elegant and mysterious, and very hot.  You just have to put up with a fairly significant "cheese factor".

Koi to Dangan - Another one with a distinct "cheese factor", however wooooo baby some of those scenes.  The ML delivers some incredibly spicy lines in there that will have you fanning yourself to cool down.  It's another one of those "racy J-dramas", and there's parts so corny you will cringe-laugh.  But the payoff is there in the way of sexiness and chemistry.

Crazy Love - Some spicy kiss scenes, and kilig moments all over the place.  It's the same ML who had that infamous super-spicy kiss-scene in 'Her Private Life'... I guess he's never afraid to bring the heat when he plays an ML role.  Unlike 'Her Private Life', this drama isn't just hot in one or two spots, it's kind of more hot-all-over-the-place.

Less scorchy & spicy, kind of on the milder side -- but still with a fairly decent chemistry level:

My Roommate is a Gumiho - There is something about that ML that's so.... intriguing and swoony.  The storyline has a lot of situations that bring a good undercurrent of kilig to the drama, and all you have to do is overlook that A) this drama isn't going to reach that height of intensity you probably crave and B) FL spends a lot of time in a tragic pair of mom-jeans.

Koi wa Tsuzuku yo Doko Made mo - a cutsey and kind of vapid story, but the ML/FL have an unexpectedly good chemistry that can get pretty intense at times, so I thought it was entertaining, although imo it's not exactly high on my rewatch list.

Doom At Your Service - less racy or heavy, and more emotionally satisfying.  But there was definitely enough chemistry there to make this probably in my top 20.

Tale of the Nine Tailed - Kind of mellow, but this was one of those roles Lee Dong Wook really was pretty sexy in, and he definitely had MY attention, lol.

Lost Romance - The story is interesting and engaging, and it has something kind of like a "What's Wrong With Secretary Kim" scene in it., only the FL isn't a workaholic employed by a slavedriver ML.  It's got some real spice in it.

The Long Ballad - that 2ML/2FL relationship has a wicked amt of chemistry, although really not any super spicy scenes in the conservative chinese fashion.  Still worth the watch imo, if you have the time to invest.  I wasn't the only one who only cared about the 2FL/2ML storyline by the time the drama was finishing, just because WHOOO-baby, that 2ML... he brought the fire.

Marmalade Boy (japanese version) - not the spiciest thing I've ever seen, but not bad... a level up from the usual flat romance drama.  The storyline was a little bit vapid, but it's decent enough cheap thrills.

Meteor Garden (Taiwanese) - Taiwanese version of BOF... the ML and FL have really awesome chemistry and that's the reason this is my fav version of BOF.  The ML is just angsty as all get out, and exudes a wild magnetism that makes this a fairly satisfying watch.

Behind Your Smile - Amazing charisma by the ML, and really steamy sexual tension between ML and FL.  However, the drama is very draggy, some aspects were really annoying, and the great chemistry between the ML and FL is dampened severely by about 2/3 of the way through so whether it's worth the watch or not is up to personal preference.  It's kind of like mining a huge hillside for just a few ounces of gold.