Ark/Arc(h) Seijin is the most vicious of the escaped Sargasso prisoners The self-proclaimed Emperor of Space, Ark Seijin once wiped out the Kein Seijin, leaving only a single survivor in the warrior Lian. Arriving on Earth, Ark Seijin initiates a series of brutal attacks that leave multiple civilians dead while taking a special interest in torturing Lian. After he decides Earth has resisted him too much, Ark Seijin uses his technology to freeze the entire Earth, which will kill every living thing on the planet, on nothing more than a spiteful whim.
Super Lifeform Genocide, the self-proclaimed ultimate perfection in the universe, is the ultimate Big Bad of the entire series, having been revealed to be behind the Sargasso Space Prison takeover from the beginning of the series. Throughout the series, Genocide regularly released deadly prisoners from Sargasso and subtly pushed them to attack Earth, where they carried out various plans that involved the mass slaughter of humans across the planet. Once arriving near the Earth's orbit, Genocide controls the Dagwon group to fight each other to the death for his own amusement, and then attempts to merge with the entire Earth, turning each and every living thing on the planet into a copy of himself and having them butcher any humans who manage to escape his merging wave.
As always, kids were the target audience, but the Bishōnen main characters attracted women older than that. Realizing this, they started playing it up somewhere around halfway through, and cranked it up for the OVA.
The villains, resembling those of an Ultraman show (Ultraseven especially), also attracted older fans.