I've just discovered that fujimi shobo's digital reader service
BOOK☆WALKER has made most of it's recent publications available through their online store.
Bookwalker carries RisingXRydeen, Highschool DxD, Boku-H and many others.
You can buy them for the same price a Japanese buyer would have to pay for at the store without having to go through a third party vendor, or pay for extra taxes and shipping, all you need is an Android phone, tablet, or iPhone.
You cannot extract the LN in a readable format from your device however.
Sadly the application is region restricted and will not be available for non-Japanese users.
But there is a way around it.
I'm not going to post the instructions here, nor am I going to help just anyone who contacts me.
If you are a translator and wish to know how to buy and download fujimi shobo novels to your smartphone device to improve translation speed and efficiency and cut down on costs as well as delivery time, then contact me.