bad boy turns into a good guy.

That's a really common drama trope and falls into various degrees of 'bad boy to good guy'. Check out Holy Land, King2Hearts, and Shut Up: Flower Boy Band.

I don't think Holy Land really fits this description.
I just finished watching it today and he wasn't exactly bad boy to begin with and romance is so subtle and it's not actualy the girl who turned him back into good boy but her brother.
On the other hand I really liked that short drama.

My recommendations are:
Autumn's Concerto - very typical example how bad boy turns into good with girl's help and a good drama.
City Hall - he has hidden motives
Last Cinderella - I wouldn't call him exactly bad but his motives just like in City Hall aren't good at the beginning.

lexies wrote: I don't think Holy Land really fits this description.
I just finished watching it today and he wasn't exactly bad boy to begin with and romance is so subtle and it's not actualy the girl who turned him back into good boy but her brother.
On the other hand I really liked that short drama.

Spoiler: Kind of figured he went crazy trying to be the best fighter. The only thing that would make his heart beat is fighting people, until he meets the girl. Her brother directed him to change his life, but the girl who made his heart beat was the who made him realize he was still alive. I'm sure she was the goal. If not specifically her, then women in general. And I was thinking that bad boy would have degrees of what's bad. Like hyun bin in secret garden is a jackass and rain in a love to kill is brooding with only revenge on his mind. So it fit's when you think of the drama trope having levels of bad boys.

Though, as paquito-d9 says, it's so common we can basically pick any drama and get that specific drama trope.

Koizora

HAVA-RAVA wrote: I'd like to know if there are the opposite haha XDDD

Like good girl gone bad or good boy gone bad.
Or bad girl gone good also XD

Nagareboshi was sort of bad girl gone good.

i think these drasa are good for you

cruel romance
kill me heal me
Falling for Innocence  
love me if you dare

Give My Tutor Friend a try