Anonysis The main story of this is in a tankoubon by Katsurai Yoshiaki called Kokuhaku Lovers. I couldn't upload it yet because it's larger than 100 MB.
Hmm... Interesting look into a life where polygamy is normal and accepted and all the wives love each other as part of the family. If the author was trying to make that familial love non-comparable, I think he did a pretty good job of it.