I'm looking for jdramas that has romance and a serious theme, not a romantic comedy. Older dramas are preferred however if it is good you can list some new ones as well.
These are the ones that I've watched. I have some more on my ptw list that fit your criteria but can't say if they're good or not
mecchaumai:Soredemo, Ikite Yuku
Its good but I don't count it as a romance.
Here is some couple of J-Drama with romance and melodrama themes:
1 Litre no Namida
Boku no Ita Jikan
Dear Sister
Hirugao
Gomen, Aishiteru
Ninkyo Helper
Guilty Akuma to Keiyakushita Onna
Love Relationship
Deep Love
Kou Kou Kyoushi 2003
Pride!
Pride
Byakuyakou
1 litre of tears
Algernon no Hanabata
Nagareboshi
Love shuffle
Love Song
Love that makes you cry
Soratobu Kouhoushitsu
Mars
Buzzer Beat
Boku no ita jikan
Taiyou no kisetsu