Drama/Romance something sad,Reality,School-Like Lovely Complex

I wouldn't say they are necessarily like Lovely Complex, but    
http://mydramalist.com/564-yamada-taro-monogatari   is a school drama about a really poor guy going to an elite school, and it is also based on a manga.

And it's not based in a school setting  but   http://mydramalist.com/11422-tamagawa-kuyakusho-of... is in my opinion pretty good, and while it doesn't seem to be based off any manga, it kind of has a bit of a manga-type feel to it's comedy, and despite  being a zombie show, it's not actually very action/horror style, it's more of a comedy

1 Litre of Tears, since you mentioned sad in the Title.
The main character is in highschool and so is the love interest, obiously ;).
It features a romance, eventhough it's defenitly not the main focus, I#d still recommend it, especally since you asked for a ssad drama. :)

highschool you like?

Gakko ja oshierarenai

Here are some live action movies and dramas based off manga:  Zettai Kareshi, Bokura ga ita Zenpen, Clover, From Five to Nine, Heroine Disqualified, High School Debut, Hot Road, It Started with a Kiss (there are many adaptations of this story), Kanojo wa Uso Wo Aishisugiteru, Kimi ni Todoke, Kimi wa Petto, Kinkyori Renai, Kyou wa Kaisha Yasumimasu, Kyou, Koi wo Hajimemasu, L♥DK, Minami-kun no Koibito: My Little Lover, Orange Marmalade, Ouran High School Host Club, Seven Days: Monday - Thursday, Strobe Edge, Sukitte Ii nayo, Yamato Nadeshiko Shichi Henge. Hope you can find something you like / this was helpful.