The 21st Attack on Titan manga volume is going to be released on Friday, December 9, revealing news about the premiere of the second season. Specifically, on the wraparound jacket band it is stated that the new anime series will premiere in April. The second season was originally announced in November 2014, but was finally scheduled for spring 2017.

Hajime Isayama launched the manga in Bessatsu Shōnen Magazine in 2009, while the first 25-episode anime series was released in April 2013. The manga has also inspired many spinoff manga, novel series, two anime films released in 2014 and 2015, one live-action film and a live-action television series. In fact, two of the spinoff manga, Attack on Titan: No Regrets and Attack on Titan: Junior High, received anime adaptations of their own.

Source: animenewsnetwork.com