Fans will have to wait until spring of 2017 for "Attack on Titan" Season 2. The delay is caused by animation development and the lack of chapters to justify the number of episodes in the new season.

"Attack on Titan" secret of the wall (spoilers ahead for those who don't read the manga)

It is always assumed that the wall in "Attack on Titan" was made by humans to ward off the man-eating mindless giants; however, it seems that this is not the case. "Attack on Titan" Season 2 will address the issue of the wall, and the Titan's connection to it.

At the end of "Attack on Titan" Season 1, a Titan tried to climb the wall to escape Eren Yeager and the Survey Corps. During the battle, Mikasa Ackerman damages part of the wall exposing part of a mysterious Titan's face within. The damage is immediately ordered to be covered so as not to allow sunlight to reach the Titan within.

Apparently, the Phantom Titans make up the walls that protect what is left of humanity. The Phantom Titan are similar in appearance to the Colossal Titan, the only difference is that the Colossal Titan has exposed bones on top of its musculature. Furthermore, A Titan bigger than the Colossal Titan will make an appearance in "Attack on Titan" Season 2 having Beast Titan in the form resembling that of a Gorilla and reportedly intelligent, according to Nerdist.

"Attack on Titan" Season 2: Origin of Eren's power

It is implied that his Doctor Yeager forcibly gave Eren's power. The connection will be traced with the basement key he gave, according to MobiPicker. The manga clearly showed that Dr. Yeager turned Eren into a Titan who ended up being eaten by his son. The corps finally got into the basement and found where Eren's key will fit in one of the desks.

It would be an exciting "Attack on Titan" Season 2 if it will be true to the manga, as it was in the first season.