This is a really difficult situation!  I have a few thoughts, and I hope they are of some use to you.

1. Perhaps you could quantify, over the course of all the tales you have studied, the number of encounters that are god to god and god to man.  I do not know much about Japanese mythology, but in most mythologies, there are encounters between gods and man and also encounters between the gods themselves.  Such a graph might be a bar graph comparing the two.  The table would lay out the data in table form, of course. 

2. It might be possible to quantify the "power" of the gods. There is usually some sort of hierarchy among them, with one having the most power and others having lesser degrees of power. This, too, could be shown with a data table and a bar graph or pie chart. 

3. If these gods are a violent bunch, their violent deeds could be quantified, too.  Or there might be a comparison of how many instances there are in which they have hurt humans or helped them.  Most mythologies I am familiar with would provide comparisons like this.