Naughty, flirty But nice ML

• Plus Nine Boys - definitely hits all ypur requirements
• WWW: Search
• Tale of Nokdu
• Maybe:
  • Pride - has the naive FL
  • Find Yourself - the FL is strong but has her perspective skewed to having that standard expectation
  • Warm and Cozy - the FL did grate on me for being 'naive' borderline stupid
  • Sweet Revenge / Revenge Notebook - naive & innocent d/t age but slowly gets her backbone in a very good way.

 Megha :

Please please recommend some drama (any language) which has ML  really Flirty and naughty . I mean, the kind of guy that knows what he wants and goes for it when it comes to the female lead. Especially if he's a little naughty.  And strong and cute FL(not stupid or naive )

• I Need Romance 3 (2014) - I wouldn't quite call the ML naughty exactly, but probably cheeky and certainly persistent / someone who knows what he wants and goes for it.  The FL is not very good at understanding her own feelings. Apart from that she's not naive / stupid. Edit: some romance and definitely some good fluff, but also occasionally a little bit melo. Nothing too heavy though.
• My Secret Romance (2017) - This one feels a tiny bit like Something about 1%. The FL is a bit naive.  Edit: Plenty of fluff and cliches.
• Descendants of the Sun - It's definitely not an old hidden gem, but it meets your criteria for the ML and FL. The ML is very flirty and knows what he wants. The FL is strong, cute and smart. Edit: also not really a fluffy rom com. More of a melo / action romance with some fluff.
  
• Sound of the Desert (2014) - Technically the FL is a bit naive (she was partly raised by wolves) but she's pretty capable / strong and not stupid.  Edit: Definitely fits your criteria for the ML and FL but it's not just a fluffly rom com - there's a very melodramatic love triangle plus some action and palace drama too. The ending is pretty happy for the main couple but pretty sad for the SML.  

Based on the additional criteria, these ones might not actually be what you're looking for. 

• The Eternal Love - ML is 100% cold and aloof in the very beginning, then cold but forward / cheeky, and then very quickly becomes very flirtatious / romantic / affectionate once he completely falls for the FL. The FL is not particularly smart. Edit: there's definitely a fair bit of comedy and tons of fluff, but also a little bit of action / palace drama. The ending of the first season is open and the ending of the second season is happy.  
• The Story of Ming Lan - It takes the ML a while to figure out that he wants the FL, but once he does he definitely goes for it and is very flirty / a bit mischievous about it. Unfortunately you'll need to wait 20+ episodes to enjoy it and there isn't much skinship. Edit: definitely not a fluffly rom com (there's political and family drama in addition to the romance, and not much comedy) but the ending is happy.  
• Before We Get Married - ML is too much in the beginning. Beyond just "naughty". But he realizes he cares about the FL and adjusts his behaviour. Still persistent and flirty though. The FL isn't exactly naive, but she makes frustrating choices that seem dumb sometimes. Edit: I wouldn't describe this as a fluffy rom com, there's a fair bit of angst / melo to go with all the sexual tension and flirting. The ending is slightly open, although implied to be happy.  
• The King's Woman - The ML basically holds the FL hostage, so he's a bit more than just naughty, but he definitely knows what he wants and goes for it.  Edit: definitely not a fluffly rom com the ending is slightly open but heavily implied to be tragic.  

 AH :

Sorry I missed these parts. I'll edit my post above. 

Thank you so much.. will definitely add above dramas to my PTW

 emi:

My Little Happiness (2021) - fluffy chinese rom-com with a very forward & flirty ML + a strong FL + LOTS of skinship

Thank you but I have already seen this drama  but this exactly what I am looking for..  

she would never know : ML is in love with FL from the start and goes for it. Also, his character is really caring and nice. FL is not naive + it has good kiss scenes

Cdrama Hidden love 2023 ❤️ ? let me know if you found anything as sweet as something about 1% 

My Dearest - Although it's a historical melodrama, but the ML is definitely naughty, flirty. The smart FL is also getting strong after eps 3.