It's easy to get confused by deflationary economies: you must think the other way around.

Since I can sit on my money and be happy, I will obviously ask for something more if you want a loan.
Let's say I factor in 2.5% default risk plus 2.5% profit, I'll still ask you a 5% interest on your loan.

People should stop thinking that "deflation is magic": it isn't. Absolute values don't matter: what matters are how much you are rich relative to other people... if money deflates for everyone, then it's not an issue. And since people want to try to get richer, they will still try to invest them, hoping to get more than they would get just thanks to the deflation.