"Attack on Titan" Season 2 is expected to air its premiere episode on 2017 in Japan. In the upcoming season, Eren Yeager will discover the real purpose why the Survey Corps is formed.

What's Inside Dr. Yeager's Basement?

The late Dr. Yeager left the key to his son Erin, who eventually joined the Survey Corps. There are speculations that Erin will find out that the Survey Corps was specifically formed to search for his father's basement, according to Mobipicker.

What's inside the basement anyway? The military believes that it contains information regarding the origins of the Titans, and may also possibly explain what happen to the rest of humanity. Erin, however, does not trust the corps and wants to find out the truth himself before the military gets hold of the basement. Erin will get inside the basement eventually and finds out that the secret has something to do with his brother.

Another Titan Shifter Revealed

Krista Reiss is joining the Survey Corps, but the upcoming season will reveal that her father, Rod, is a Titan Shifter. The discovery will be made by Erin and Mikasa. It's unclear if Rod is one of the good Titan like Erin. If he is not, viewers may witness a clash between two Titans inside the walled city. There have been rumors that the upcoming season will feature Erin investigating the Titans breached the city's wall.

One possible reason is that undercover Titan Shifters are helping their kin in getting inside the city. Does this mean that there are more than two Titan Shifters hiding among the surviving human population? Can Erin get rid of them before humanity is eaten into extinction? These speculations can only be answered in the upcoming installment.

"Attack on Titan" Season 2, which is also known as "The Second Phase," will start to broadcast in the Spring of 2017, according to Natalie.