Under the command of Jin Mogis, the Kingdom of Arabakia's Expeditionary Force declared independence as the new Frontier Army. They then formed an alliance with the king of the goblins. Now, their next move is to conquer Mount Grief, occupied by an army of orcs.

Entrusted with an important mission to infiltrate and disrupt the enemy from within, Haruhiro and his team work with the members of Shinohara's Orion, Team Renji, and the Tokkis in order to break through the "Graveyard" beneath Mount Grief. However, the mission proves more difficult than they imagined, and they are faced with nothing but close calls and dangerous foes. Forget about taking Mount Grief, are they even going to be able to survive this?!

Fighting alongside old comrades. Feeling conflicting emotions during a battle to the death. Is the team headed toward hope or despair?