People and organizations can get around sanctions but it introduces complications, slow downs and added costs. A good example of this is the sanctions on semi conductors that Russia needs for missiles. Since Russia can't get them directly intermediaries in Central Asian countries will buy large amounts of refrigerators and washing machines from the west. These are then sold on to Russia where they are stripped down and the semi conductors are removed and then reconfigured for missiles. It is time consuming, expensive and doesn't produce the missiles in the desired quantities for waging a large scale war. Will Japanese sanctions stop Wagner? No. Will they make it more expensive and harder for Wagner to operate successfully? Probably.