Anime series "Attack on Titan" has been set to return for a second season. According to its creator George Wada, season two is already in the works as its production already began last month, although there has been no official premiere date announced.

Written and illustrated by Hajime Isayama, the Japanese manga series follows the story of humans who struggle to protect themselves from the Titans – giant creatures who attack and devour people for no reason.

As the world gets nearly wiped out by such giants, a country that is protected by enormous walls has been left, allowing the surviving humans to live in peace.

The highly-acclaimed animated series adaption has attained considerable fame despite being aired within a short period last year. Last July, the "Attack on Titan" manga bagged the award for Best American Edition of Foreign Material category at the Harvey Awards.

The manga soared to the top of the list of the biggest-selling graphic novels in Japan and North America, selling over 40 million copies before the month of July ended.

As the first season concluded in September 2013, the "Attack on Titan" season two is expected to be aired on August 2015.

Furthermore, its spin-off "Attack on Titan: No Regrets" is also being reportedly released, separately showing at least two new episodes on Dec. 9, 2014 and April 9, 2015. This will take place alongside the release of the 15th and 16th volumes of Isayama's manga series.

The first season will also be broken down into two movies that are to be released separately.  The first is entitled "Crimson Bow and Arrow" which will premiere on Nov. 22, while the second called "Wings of Freedom" will be released in 2015.

A compilation film for the "Attack on Titan" entitled "Attack on Titan: Guren no Yumiya" will be shown at the upcoming Tokyo International Film Festival from Oct. 23 to 31. All in all, 13 screening episodes of the anime series will be featured.