Kaio (referred to as the Beast-King by lore) is an Ultimate Form Spectrobe, which is contained inside a currently unnamed Geo. Unlike other Ultimate forms, he/she/it is made up of five divided fossil shards spread across the galaxy.
It is unknown if Kaio has been summoned at all prior to the events of Spectrobes: Origins. However, it is possible since the Green Ruins in the Tree of Life have pictures on some of its walls showing Kaio facing a creature, which appears to be a Krawl, specifically Darkroe.
At one point, Kaio was placed in the form of a fossil that was divided into five shards, which were scattered across the several planets of the Kaio system.
Kaio is summoned by Rallen and Jeena after defeating Jado. At Mt. Awakening on Wyterra, the two are able to place all five segments of its fossil in the five shafts of light on the pool on top of the mountain. The Ultimate Form obeys the order from Rallen to defend Wyterra and destroy the approaching Krawl army, as well as Jado. After this, it returns to dormancy, this time in the form of a Geo. In this state, it communicates with Rallen, telling him its name, as well as that its power will be needed again soon.
The Ultimate Form is once again summoned by Rallen after defeating Krux in the Krawlosphere. In the core of the Krawl planetoid, Rallen activates Kaio's Geo, summoning him to attack the core. The attack is successful, and causes the entire planet to freeze over and break apart.
Kaio is dragon-like in appearance. Similar to Grildragos, it has two arms, six wings, and a tail, but no legs. Its body shines in a light blue color.
- Unlike every other Spectrobe in Origins, Kaio does not have a proper in-game model, only appearing in two pre-rendered cutscenes; naturally, this also means that it is the only Spectrobe in the series to lack a database entry, and is the only Ultimate Form unable to be summoned in battle.
- Due to it sharing a name with its system, it is safe to say that Kaio might be close to a Guardian or Creator/God of its system.