Episode 8 of Kamen Rider Kuuga, the Heisei series that brought it all back.

Long ago, the Grongi Tribe were defeated and their leader was sealed in a cave by the warrior named Kuuga. In modern day Japan, researchers have discovered the tomb and unwittingly released the Grongi leader who, in turn revives his brethren and they begin killing humans. Godai Yusuke, a multi-talented young man is drawn to a mysterious stone belt that was also excavated from the ruins…

Torrents and DDLs for the subs can be found here http://scs-works.blogspot.com/