Arthur 7
Well!
So the summary of the goes on like:
The world has many humans, but there are some humans who gain mysterious ability against human nature. They are known as Ability Users. They are not accepted by human, feared and are discriminated against.
We follow the story of a normal guy who is one of the Ability Users.
Arthur, as a kid, he feared by all the other children of his age. He was given the name of the monster, freak, and everything because he was always different from other kids and seemed to change his personality completely. His ability seems to be an odd one so noone ever found out about him being and Ability User.
Because of that, he was alone most of the time not accepted anywhere, living a boring life which fell apart soon.
One day a mysterious girl who had weird powers crashes through his window.
Once again he became a monster in order to save that mysterious girl.
Her name was 7.
(7 was in an organization full of Ability Users fighting against the government.)
She was the first person to still smile at him after seeing his monstrous side of him without fear. And so he fell for her at first sight.