Locating unknown relatives

My father was a pilot and flew to Japan for many years. He loved Japan and its people. We are pretty sure he a mistress or a girlfriend in Tokyo. There have been a couple of relatives and a friend that have vaguely hinted at my brothers and I that we may have a step brother/sister we don’t know about. (“I wouldn’t be surprised if you guys have a half brother over there.” Or, a fellow pilot who didn’t know I was his son and didn’t notice me, said with guy-code admiration, “I heard about your operation you got set up over there, Marty!”

My brothers and I would like to try to find out if we have a half brother/sister, but we don’t have the slightest idea of how to go about it. I don’t think they were married, so I don’t think it would be as easy as looking up our last name in a Tokyo directory.

Any ideas?

How about even known? My real dad died years ago but I know I have half-siblings, and while I don’t want to mess up their lives, I’d sure like to find out about my dad’s wife.

Unfortunately she’d probably think of me as a product of sin. :frowning: