This is just an idea, but given that the Arcle was taken by Onodera and Narutaki near his resting place, his belief that he should have never awakened, and his ability to make Gurongi out of humans might have meant that he was this A.R.'s Ancient Kuuga.
- Sealed in a place where a Kuuga should have been to power an Arcle Seal.
- Believing that he should not have awoken means that he was there to rest by his own volution (or generally sealed himself)
- Making Gurongi from humans and absorbing their power (must have been the reason why he sealed himself)
Two tattoos?If N-Gamio-Zeda didn't exist in the original Kuuga series, why does he have a tattoo from that season apart from the one in Decade?