Looking for a manga

i read a manga a very long time ago ( i cant even remember when did i read it)
it's a oneshot that set in war time, with romance(kind of) and psychological tag. The mc was a girl who had lost her parents, she met a guy who was a bio-weapon (a part of his body is machine). She wanted to kill the guy to revenge for her parents but didnt succeed. The guy spared her life and offered her money to leave the city they're in for safer place but she didnt accept it. The girl then followed and lived with the boy.
Because the guy was a bio-weapon, he had to have a kind of drug from the organization that made him but he had to finish his killing missions in order to obtain the drug. Since he left with the girl, the organization no longer gave him drug. Later, a co-worker of his showed up and tried to convince him to come back, he didnt agree so the co-worker tried to kill the girl. The guy fought the co-worker to protect the girl.
In the end, the guy died, the girl lived to ripe old age but never forgot the guy, the last scene was the girl telling her story to a reporter.
yes, i managed to remember the whole plot but not the fucking tittle ╥﹏╥