Watch Terra Formars: Earth-hen Online

Bundled with the 21st and 22nd volumes, the OVAs adapt the Earth arc of the manga.

With the space program attempting to travel to Mars, 21st century scientists were tasked with warming up the planet so that humans could survive on its surface. They came up with an efficient and cost effective plan of sending cockroaches and mold to the surface so that the mold would absorb the sunlight and the insect corpses would serve as a food source for the mold. It is now the year 2577 and the first manned ship to Mars has landed on the planet and the six crew members are ready for their mission. But what they find are giant mutated humanoid cockroaches with incredible physical strength. The crew members are easily wiped out, but not before sending a transmission back to Earth. Now, humanity will send elite warriors to exterminate the mutated bugs and claim back Mars.

In the late 26th century, overpopulation on Earth is reaching the breaking point, and humanity must find new frontiers. The terraforming of Mars has taken centuries but is now complete. The colonization of Mars by humanity is an epoch-making event, but an unintended side effect of the terraforming process unleashes a horror no one could ever have imagined... After humanity's first manned mission to the Red Planet was lost, a second expedition arrives. The explorers prepare to exterminate the cockroaches that were used to transform the Martian environment. They are shocked to discover that the insects have mutated into giant, aggressive humanoids with one overriding goal — exterminate the humans! But this crew of explorers has each undergone the Bugs Procedure, terrifying experimental surgery designed to make them more than human...

In an attempt to colonize Mars, 21st century scientists were tasked with warming up the planet so that humans could survive on its surface. They came up with an efficient and cost effective plan of sending cockroaches and mold to the surface so that the mold would absorb the sunlight and purify the atmosphere, while feeding the insects whose corpses would help the mold spread throughout the planet. Five hundred years later, the first manned ship to Mars lands on the planet and the six crew members are attacked by giant mutated humanoid cockroaches with incredible physical strength later labeled as Terraformars. Before the crew members are easily wiped out, they manage only to send a transmission back to Earth. Decades later, a multinational expedition is sent to exterminate the mutated bugs and take control of the planet just to be wiped out as well, except for two survivors who managed to return to Earth, with one of them swearing to one day return to Mars and avenge their fallen companions. As a third expedition is assembled, questions are raised about the true origin of the Terraformars and their connection with a mysterious disease that is afflicting mankind back on Earth.To fight the Terraformars' strength and agility, the members of the second and third expedition undergo genetic modification to inherit the characteristics of other organisms, only possible after having a special organ implanted inside their bodies with only a 30% chance of surviving the surgery.