Aldebaran

Aldebaran is a Stage IV Gastrea that appears during the Third Kanto War arc. It is named after the brightest star in the Taurus constellation, due to the fact that it was known as the "right-hand man" of the Stage V Gastrea Taurus, during the early years of the Great Gastrea War. They were infamous for their organized attacks in many parts of the Asian continent, with Taurus being near-invincible and Aldebaran being able to secrete swarm pheromones to control the other Gastrea. After Taurus' defeat by the IP Rank 1 Initiator, Aldebaran reappeared during the Third Kanto War arc, latched itself onto Monolith 32 and injected Varanium corrosion fluid into the Monolith, destroying it within a few days. It then lead an organized attack of around 2000 Gastrea against the self-defence force and civil officers of Tokyo Area, leading to the commencement of the Third Kanto War.

Along with its pheromone secretion and its corrosion fluid injection ability, Aldebaran also regenerates at an unbelievable rate. Commander Gado stated that Aldebaran "will not age or die", after having split open its head and stabbed its chest with his Varanium sword. The only way that Aldebaran could be killed was if it was destroyed completely and thoroughly, until not a single piece of it remained. As a result of knowing this, Aldebaran's death was caused by the EP (ekpyrotic) bomb provided by Shiba Heavy Weapons, which was planted in the stomach of Aldebaran by Rentaro and set off by Shouma, finally annihilating it.