I cannot help with any recipes, but I’ve had my share (actually more than just my share) of Nama chocolates when living in Japan and I can not agree to your statement that
11 hours ago, porfyra said:they do not have a very strong chocolate taste
All the varieties I’ve had (including the lovely Matcha one) have a quite intense flavor, and not only from the powdered coating but the core as well. I think @JeanneCake’s suggestion of a “simple” powder-coated ganache would be a good starting point.