After seeing this data vis presentation, I thought a small multiples view of JGB yields would be a nice additional view of how yields have moved since 2012. I gathered the data in R and then fed the data to a d3 plot through a clickme ractive. To see the entire ractive structure, see this git repo.
A nice addition to this would be a yield curve that changes as a user hovers over the yield charts. If they hover over the 40y for March 1, 2012, this yield curve chart would plot the curve for all maturities for that date. Also, a line would move across the dates in each yield chart to allow a easy date reference.