I'm looking for a good J-drama that I haven't watched. Any genre is fine but I have some requirements. (─‿‿─)

1. It has to be a TV series of at least 12 episodes or more. No long-running series please.
2. Good acting please. The last J-drama I watched, the acting was too awkward.
3. A good and happy ending with closure. Open-ending drama and sad endings are things I can't handle.
4. Umm...although I don't mind the genre, I'd prefer if it wasn't completely focused on romance. If it does, it's fine though,
as long as it's really good.
5. And last, please don't give me something too old....umm anything after 2000 if fine.

Thank you! <3 

All of the J-dramas I've seen have run for 9 to 11 episodes, discounting second seasons, SP's, and films. That said, in keeping with the rest of your guidelines:

Biblia Koshodou no Jiken Techou
Love Shuffle (romance focused, but not just on one couple, and SOOO good)
Mop Girl
dinner
Umi no Ue no Shinryoujo
Thank you. I'll try those.
I think all these dramas have around 10-12 episodes, and a happy ending; these are the ones I would recommend:


Atashinchi no Danshi 
Mei-chan no Shitsuji 
The Memorandum of Kyoko Okitegami 
Yamato Nadeshiko Shichi Henge 
Sprout 
Gokusen
Kaitou Tantei Yamaneko 
Nodame Cantabile 
Kanojo wa Uso Wo Aishisugiteru 
One Million Yen Girl 
Orange Days 
Kingyo Club 
Otomen
Ouran High School Host Club
Celeb to Binbo Taro.

Thanks for recs. Besides Ouran, I haven't watched the others.
It's really hard to match your criteria of 12+ episodes, but these are the J-dramas I highly recommend:

3 nen B gumi Kinpachi Sensei 6
Ashita, Mama ga Inai
Attention Please
Priceless
Mother
The Queen's Classroom


Sunao ni Narenakute (not 100% sure about closed/good ending though since I can't rememeber)
IS - Otoko Demo Onna Demo Nai Sei (same)
Last Friends (same)
Nobuta wo Produce

Good romance dramas:
Tatta Hitotsu no Koi 
Anego

(as mentioned before 12+ episode jdramas are rare. these are all 10-11 episodes)