They're founded later than Data East, but also Japanese. They don't appear to be any sort of spinoff of Data East or anything, but I have to wonder if with the name they were hoping to confuse people somewhat into thinking they were Data East, or to ride on their reputation...
Wait, Data West? Apparently there was indeed such a company: https://www.mobygames.com/company/6613/data-west/
They're founded later than Data East, but also Japanese. They don't appear to be any sort of spinoff of Data East or anything, but I have to wonder if with the name they were hoping to confuse people somewhat into thinking they were Data East, or to ride on their reputation...