Youji Hino shows the newly developed Mark Sein to Mjolnir and wants her to give it to Kazuki Makabe. Mjolnir boards Mark Sein and defeats the Festum that is about to destroy the Gnosis Model Kazuki pilots. Mark Sein lands before Kazuki and Mjolnir exists the cockpit. Kazuki boards Mark Sein after his conversation with Mjolnir and proceeds to battle the Festum that ate Mjolnir. Releasing a huge amount of energy, Mark Sein sinks into lava and takes the other Festum with it. In its place, a huge lava monster appears which ends up eating itself and transforms into a lava rock from which Mark Sein emerges without its back equipment.

Mark Sein arrives just in time on Tatsumiyajima and nullifies the enemy's attack. It then gets surrounded by small enemies, but Mark Sein assimilates them. It grabs the Garm-44 from the ground and the Luger Lance from Babalon and strenghtens the power of both weapons to take the enemy out.