Attack on Titan: Difficulty (2014)

In the year 848, the recruits are split into two groups for a wilderness exercise to learn how to sustain themselves in times of peace. Marco has trouble leading his group due to the arrogance of both Eren and Jean.That night, the thieves ambush Eren's group, taking Krista hostage along with their equipment. Putting aside their petty squabbles, they must team up together to rescuing Krista.