Problem
Both the High School DxD Anime and Manga found resounding success in the west with the anime on MyAnimeList citing a popularity rank of 59 on there entire site with 633,450 viewers and the Manga being on the New York Best Sellers Top Ten 8 times since it was licensed in 2014. Unfortunately the novel which the original source material hasn't been noticed.

Solution
Someone reached out to the J-Novel Club on there Twitter asking about a petition to show them the market for the novel and got a reply of with 200,000 signatures with an estimated 1% being buyers, and they will consider it. Since it has been 2 days and not one started one I did, so if your interested in being able to buy the novels please sign.

https://twitter.com/jnovelclub/status/1064747591424987137