When I wrote this post, I stupidly forgot (BWI, likely) about the legislative proposals to tighten political financing reporting requirements. Here, the two sides are working furiously not to look bad in the public eye, which means that they have to come up with a compromise. The LDP does not want total disclosure, the more presentable excuse being that it would be too costly and time-consuming. I'm surprised that no one on the DPJ side appears to be making the point that, in reporting, all the receipts and accounting books could simply be digitally photographed (if not already available in some digital format), posted on a secure site, and made available for anyone to download. The original documents can be referenced when there is doubt.
Note that the agreement in principle to report every expenditure item down to the last yen follows Ichiro Ozawa's original proposal, which the DPJ itself had vetoed back then.