Leaf identification? Like a maple with seven lobes?

Question

Can you help me identify this tree? It's growing in my yard in Northern Japan (Hokkaido), and has a very spiny trunk (it's just a baby -- maybe one or two years old). The leaves are very big -- maybe six to eight inches across, and they look like the Canadian maple leaf (sort of) but with seven lobes -- very smooth edges, but distinctly star-shaped.

I'm wondering if I should let it grow, or just chop it down. It looks very healthy, even though it's only about 18 inches high right now.

Answer 1

castor bean/oil plant?

Answer 2

it may be salmalia malbarica. It is a eautiful tree, don't cut it