The Silver Imperial Army Zone is an alien army that seeks to rule the Milky Way. Traveling aboard the massive galactic battleship Vulgyre, Zone has already destroyed 999 planets and targets Earth as its thousandth conquest.

If Zone succeeds, its ruler will gain eternal life.

Milky Way Emperor Medor is the mysterious ruler of Zone, characterized as a white-skinned, silver-maned figure with purple lips and golden eyes.

The truth behind Medor is tied directly to the nature of Vulgyre and the final, dark secret of the empire.

Vulgyre is Zone's galactic battleship and the empire's primary mobile base. It carries the army across the universe as Zone relentlessly searches for its thousandth planet to destroy.

Garoa is the captain of Vulgyre, distinguished by his black and gray armor worn over red clothing. Armed with a sword, he commands Zone's operations against Earth and harbors a deep, personal grudge against Gaku Hoshikawa.

Doldora is a high-ranking female scientist in gold armor over black tights who supports Zone's schemes with advanced technical knowledge and tactical battlefield plans.

Zaza is Doldora's loyal underling, wearing black tights with purple armor and assisting her during various operations.

Billion is renowned as one of the greatest swordsmen in the galaxy. With a white mane and white armor over blue tights, he serves as a dangerous, elite warrior within Zone's command structure.

Dongoros is a grotesque, short, and greedy space merchant who is obsessed with accumulating Dolyen bills. He carries an abacus and views the conquest of planets strictly as a business opportunity.

Shubalie is a former captain of the Vulgyre who returns as a formidable enemy. He utilizes weapons such as the Barok Stick, Barok Fencer, Barok Shoot, and Barok Byoot, and maintains control over a black Gorlin.

Batzler Soldiers are Zone's mass-produced foot soldiers. They feature black bodies, red heads, and crab-like claws used for aggressive close-quarters combat.

Galactic Warriors are Zone's monsters of the week, often themed after Earth animals. Later threats include Combined Galactic Warriors, hybrid monsters possessing the traits of two distinct species.

Gorlins are giant, white-skinned cyborg aliens that absorb and mimic human-sized monsters to engage in giant-scale battles.