I have been trying to figure out the exact ID for this plant for a while. Google Lens usually tells me it's some kind of nettle. It doesn't have any spines, but it does look like nettle. In Japanese ramie is called "karamushi" and it has a long history. Most people around here call the plant "hazeh" which isn't useful as that name doesn't appear in any publication I can find.
Should I just try to extract the fibers as if it were ramie and find out?