I remember reading it around the late 00's/early 10's. As in the title, the story centers around a boy and a girl who must hold hands, or else they will die. I believe the setting was fairly typical fantasy - swords and sorcery, etc. - drawn in a shounen style, with some pretty crazy character designs. If I recall correctly, the girl was magical or divine in some way (which also explains the nature of their need to hold hands), who perhaps appeared out of nowhere. The pair were then given a task by someone in their home village to travel somewhere in order to remedy their hand-holding curse.
I'm almost positive it never received an anime adaption. At the time I read it, there were only a handful of chapters available, so it could very well could have been cancelled early in its run as well.