Sentou Bokokan was a large battleship that appeared in Grendizer that first appeared in episode 28. Much like the Motherburn before it, its primary function was to store saucer beasts and minifos, later storing vega monsters and midifos starting in episode 52 when King Vega moved what was left of the Vegan Empire to the base on the far side of the Moon. It was under the command of Gandal and Zuril.
Read more about this topic: Fortresses (Mazinger)