Your friend is basically useful idiot. Yes you can tell him what I said here. As long as there are NO contractual bindings, his chance can be more of zero than going. If Japan is his intention, quit his job and look for others. Maybe dropping by Taiwan, Singapore, or HK first. My friend of 2 decade landed Japan job (internal transfer) by joining a local Asian bank with a branch in Japan. And never once they dangled to him "you could/will be going to Japan".