User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-119.160.168.204-20130208141427/@comment-33447191-20130209003903

Well, High School D×D is a fairly popular series and has sold a an estimated total of 654,224 copies ranking it 6th place in '''Top-Selling Light Novels in Japan by Series: 2012. '''

You can read it here: http://www.animenewsnetwork.com/news/2012-12-02/top-selling-light-novels-in-japan-by-series/2012

Also Highschool D×D sold a total circulation of 9,121 copy (6,780 BD + 2,341 DVD), which is an impressive feat, leading to Season 2 being announced.