Learning Mimori is at the center of the Vertex outbreak, Yūna and Karin chase after her into the Shinju, learning what Mimori herself had learned. Before they can try to reason with Mimori, who believes destroying the Shinju is the only to spare her friends from suffering, Yūna and Karin are forced to retreat from the Vertex. Yūna's confusion over the matter leaves her unable to transform into a hero, believing herself to be a failure as a friend. Wanting to fulfil Yūna's desire to stop Mimori and be together again, Karin goes off on her own to fight through the Vertex standing between her and Mimori, having to undergo Mankai multiple times in the process. As a result of the battle, Karin ends up losing her sight and hearing, as well as the use of most of her limbs, by the time Yūna finds her. Meanwhile, after Fū and Itsuki fail to stop her, Mimori attempts to destroy Shinju by luring the Vertex's attack towards it, but the attack is stopped in its tracks by Yūna, determined to protect Mimori.