Aloe vera - "true" aloe - is Aloe barbadiensis. But there are some 500 or so other species of aloe, none of which are native to Japan (so have NO idea what 'Japanese' aloe might be!!). Some are considered edible, some are not. Before consuming this plant in quantity, I'd want to confirm an identification.

And I think you would have much better feedback on any ID by posting photos of your plant on the Cacti and Succulents forum. While it may be edible to some degree, aloe is not really an herb but it IS a succulent and there are some very accomplished succulent growers on that forum who may be able to provide an accurate ID. Be sure to provide clear photos of the entire plant, a couple of leaves in detail and any flowers.