Yuusha Exkaiser Episode 11: Great Discovery at the Ancient Ruins
Episode 11 of 48 of Yuusha Exkaiser, aired April 14, 1990, 25 minutes. Available with English subtitles and dub where released.
Episode summary
When aliens plan to invade earth, the young Kouta along with a giant robot from outspace named Exkaiser must team up to save the world and his friends.