This article is about a/an transformation devices in Kamen Rider Kuuga.

The Spirit Stones (霊石 Reiseki) are mysterious items that appeared in Kamen Rider Kuuga manga.


The Maternal (母体 Botai) is a monolith size Spirit Stone that can turn human into the Gurongi or Agito.


2015 Arcle
Main article: Amadam

One of the Spirit Stones is the Amadam (アマダム Amadamu), which is the power source of Kamen Rider Kuuga.

Any given successors can inherit the Amadam from the previous host if they are willing. However, the successor will suffer great pain and see illusions when merging with it.

Alter Ring

2015 Alter Ring
Main article: Alter Ring

Another derivation of Spirit Stone is the Alter Ring (オルタリング Oruta Ringu) that provides energy to Kamen Rider Agito.

If its host died, the Alter Ring is able to transplant itself automatically to the user's nearest relatives.


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