|Gender:||Probably inapplicable, but had a female voice|
|Lives:||In space; briefly Juuban Odyssey|
|Family:||Ail, An (offspring)|
|First Anime Appearance:||Moon Revived! The Mysterious Aliens Appear|
|First Manga Appearance:||N/A|
|First PGSM Appearance:||N/A|
|English Name:||Doom Tree, Tree of Life (dub); Makai Tree (Viz dub)|
|Actors:||Taeko Nakanishi (anime), Elizabeth Hanna (dub), Erin Fitzgerald (Viz dub)|
The Makaiju (Tree of the Demon World) was the tree from which Ail and An were born and which they wanted to protect using the energy obtained from civilians by Cardians. It appeared in the middle of the night in the form of a meteorite which crashed in Tokyo.
After the Makaiju crashed in Tokyo, Ail and An moved it to a vacant apartment at the Juuban Odyssey complex, where it took root in a dimensionally-warped room, creating a headquarters and hideout for the pair.
At first, the Makaiju granted energy and warmth to Ail and An. However, this energy quickly dried up, due to the negative feelings and experiences Ail and An had carried with them from their home world. Ail and An began to use Cardians to attack and steal energy from people in order to feed the Makaiju.
The tree tried to communicate to Ail and An during their time in Tokyo, but was unsuccessful. It even went so far as to attack visitors to the apartment, specifically Usagi Tsukino and Mamoru Chiba, in an attempt to get through to Ail and An. As a final resort, the Makaiju spoke and taught Ail and An that the proper way to treat living creatures was with care and nurturing. After Sailor Moon purged the Makaiju from the stolen human energy at the tree's request, Ail and An took this lesson with them to a new home planet with the Makaiju in the form of a seedling.