Jammil

Hey y'all. I just came into possession of my late grandfather's Japanese sword. I know nothing about it besides what I've read so far on this thread and what my uncle has told me, which is very little, except that it was given to him during WWII (or taken?). Not looking to sell the sword but rather try to get the story behind it and where's it been. The wooden handle appears to be in rough shape as well as the sheeth. I've not even tried to clean this and wanted to get some ideas on restoration. Any help would be greatly appreciated.