Makaiju

The Makaiju (Hell Tree) itself is an alien tree that nourishes Ail and Ann, but has become unhealthy and requires energy to stay alive. For some time they supply it with human energy, but eventually it stops working. In the dubbed version and ADV subtitles, it's referred to as the Doom Tree. When the aliens try to give Usagi to it as an offering (as it seems to greatly like her energy), it becomes angered and starts to injure those around it, killing Ann in the process. It did not stop until its alien children real…