Up to four players can team up online to face the Titans together in Expedition Mode. These missions are separate from the main campaign, but all materials, experience, money, and gear earned carries over into the campaign. All players earn the same rewards for completing missions
The story of Attack on Titan revolves around the adventures of Eren Yeager, his foster sister, Mikasa Ackerman, and their childhood friend Armin Arlert. After the wall which protects their hometown of Shinganshina is breached by the Colossal Titan leading the other Titans to enter, Eren watches in horror as one of them eats his mother. Vowing to kill all the Titans, Eren enlists in the military, along with his friends.