

Might sound like a crazy take, but if you just make sure you (only) do what you want and are clear about your intentions towards him, you should be fine.
If you want to have a drink from some casual company until you leave - do that.
If you want some steamy sexy time for one night and then leave - again, do that.
If you really like the guy and might actually consider some sort of longer relationship - guess what, do that.
Just be clear and honest, towards him and yourself. That way he can decide what he wants from you.
And as all engineers know: assumption is the mother of all f*ck-ups, so avoid those at all cost.
I understand this makes you unsure, but I really think this would be a perfectly normal question to him: “Hey, I really enjoy your company, but I have noticed in the past with other Japanese friends that they sometimes have mistaken a hug for me asking for more. How do you see that?”
Especially with him being an older guy (which generally means a bit less insecure and more mature) I would expect this to be a good start for an honest conversation.
I hope it does work out the way you want!