I've never heard of Japanese Schefflera. I wonder if it's the S. elegantissima that is also sometimes called False Aralia? I love the leaves on that one and used to have a couple of very large and bushy trees but both were lost to winter freezes a couple of years ago. I still have a small one and they are very easy to propagate too. Here's the link to S. elegantissima in the ATP plant database:
