User blog comment:B214/Don't ask about season 4/@comment-26402117-20160527154931/@comment-1359322-20160528042615

You can hope that Volume 22 might reveal the green-lit of Season 4 like Volume 18/19 (Don't remember which volume). Either way don't put your hopes too much, Season 3 might be the last season of High School DxD as an anime after all.