In a world overrun by Titans, humankind has been forced to flee behind three concentric Walls in order to stay alive. However, the safety provided by these Walls was destroyed the day the Colossal Titan appeared, and breached Wall Maria. Eren Jaeger, a boy whose mother perished on that day, joined the military in order to take his revenge against the Titans who had stolen his freedom and destroyed his home. Five years later, the Colossal Titan appeared again, breaching Wall Rose. A fierce battle took place against the invading Titans in Trost District, during which it was discovered that Eren had the ability to transform himself into a Titan. Using his newfound power, Eren successfully plugged the hole in Wall Rose, and secured mankind's first victory against the Titans.