I have not seen that type of cleaning kit before. I had a holster from a Tokyo yard sale to my friends hands,then to me, last year. No one had seen an open type Nambu holster, just close clam shell. But that hoster was for a Japanese automatic and was Japanese by design, stitching etc. After WWII there was a lot of kit made for American military (tourists) garrisoned in Japan. You may find that kit of yours, if from the orient, could fall into this catagory.
Good luck.