While we pay 0.1% to japanese for their investments in india, where not a single japanese worker comes to india, not a single inch is given to japan, not a single share is sold to japan, not a single free zone is created for japs, not a single inch of any port given for free . Now compare and do your own math.
First, is there any proof of that interest rate? Second, the analogy with Japan is bad. How much is Japan investing relative to the size of your economy? Japan isn't investing in a trade route between India and Japan. That's what CPEC is. Completely different scenario.