sendhalp

Looking for a manga's name.)/

So I read this manga few weeks before and forgot the name-

It's about sci-fic, I think. The MC is a guy and look like Kirito at first. He's in a group where they assassinate people, the group is well known. Since he was a kid (MC), he showed great possibility and quite smart too. Going back in present, his higher up tasked him to tutor a girl. It's not just a normal girl but a royal one, although she is, it was rumored that the girl is not a pure-blooded for she can't use mana. The MC will tutor the girl on how to awake her mana and if she failed to even after 2 years, the MC will have to kill the girl.

The MC actually given up to the little girl after 2 days, he decided to kill her just to end her sufferings but then, he saw the girl's determination to learn no matter how tough it is. So he changed plans and decided to help the girl to take a medicine in which there would be a possibility to awake her mana. Even so, the said medicine is not yet completed so the possibility is low.

I can still remember the next part but what I actually want is the manga's title. The manga was a top before— romance genre.

Sorry for my bad English. c.c