Sounds like Mugen no Minamo ni, although I haven't actually read it through myself. The "time as a reward" thing matches at least.

OMG! That's it! Thank you so so much. I was thinking of this so much I barely slept in the past 3 days. I don't know why I kept associating it with shinigami alice though

Hello everyone. I'm looking for a manga I've read a few years back. It has very slow progreds at that time that's why I have completely forgotten it until recently since I started dreaming about one of its scenes. I was thinking it was shinigami alice, but ai'm not sure. Uhhh.. soo here goes.

It's about a girl that's um..is a secret assassin/killer I can't remember much but I do remember that she was asked by a classmate to kill her own father, and when she did killed him, that classmate saw her kill her dad. She has a sick girlfriend, and everytime she succeeds in a task, an oracle appears and gives her "time" to extend her girlfriend's life as a reward.

I'm not sure if i'm mixing 2 separate mangas but thats all about I can remember. Thanks a bunch.
xoxo