The Encounter: Encounter with the Known

* Based on the manga written by Sasuga Yuu and illustrated by Tachibana Ken'ichi, serialised in Weekly Young Jump.

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...

Source: Viz

Note: The two OVA volumes bundled with the 10th and 11th compiled volumes of the manga, respectively.