"High School DxD" is one of the most popular anime TV series in the past few years. It tells the story of Issei Hyoudou who somehow ends up as the servant of Rias Gremony while working with other devils in their group. According to My Anime List, "'High School DxD' is a hilarious harem anime, featuring a variety of supernatural creatures, as well as tons and tons of beautiful ladies!" Because of its funny and sexy anime harem theme, fans around the world have been waiting for the next series.
The popular anime TV series finished airing their third or "BorN" series June 2015. Since then, fans have been looking for clues on the possible release date of the fourth season. When-will.net reports, "at the moment, the TNK studio is yet to renew or cancel the anime." Although it sounds bad that it has not been renewed yet, the popularity of the anime increases its possibility for another season. The only question is on when the series premieres.
User Dark_Knight_Reddits on Reddit has a speculation about the possible release date of the upcoming series, "To give you an idea of the past timeframe between seasons. Season 1 premiere was early January 2012, Season 2 was July 2013, and Season 3 (BorN) was early April of this (2015) year (announced almost exactly a year ago in June 2014). So it could be a year before they announce season 4." If the expected timeline is followed on season three, there's a possibility that fans will get an announcement this year for next year's release.
For the upcoming season, it's expected that the story will now revolve on time travel with Issei finding himself at odds with Loki. Forum user Lolimancer at My Anime List speculates that the upcoming season will feature Loki, Issei and even Issei's children who travelled from the future to save the present.