This is a doujinshi, fan comic, by Iyokan telling the story of how Suwako and Kanako met. If you know of these two you know they weren’t always together, but we don’t know why Suwako stays with Kanako despite Kanako invading her land and taking over as god for that land. Something must have happened that Suwako and Kanako had no choice but to stick together. And this doujinshi gives an interesting and pretty good theory.
It also has an interesting, if somewhat controversial, theory on the origin of the Kochiya family.
This isn’t an ero doujinshi so the rape scene wasn’t shown.
I personally don’t like this concept. I mean, when I think of Kochiya Sanae and know of her ancestor is the goddess Suwako, I can only think as Sanae as a person with noble blood flowing through her veins, but with the Kochiya family’s originating from rape…I’m not too keen on the idea of it.
But then again, most Japanese gods were born from some sort of bodily fluid…IIRC one was born from snot and another from piss. [Can’t recall who though ^_^’]
But as a whole, this title was a very interesting read and I recommend any Suwako/Kanako fans to give it a read. It gives a different side to Suwako other than her happy-go-lucky personality.
Open Your Mind 
Then again, this is quite ‘tame’ compared to say, Greek myth. Though yeah, I agree; I was kinda hoping for a more romantic (or at least, optimistic) interpretations. Frankly, if it weren’t for that scene, I would have really liked this manga. The narrative style, relationship development between both of them were really good.