Squad 13 guards one of the facilities for the top-secret S-Planning, when Mitsuru collapses in the mid of battle. As he is treated it is revealed that he underwent a dangerous procedure with only 15% of survival rate to become a parasite when he was a child. Later, due to Mitsuru’s incompatibility with Ikuno, Nana asks the Parasites if they want to switch partners. Ikuno asks Ichigo to partner with her, but the two girls fail to synchronize. Kokoro offers to partner with Mitsuru, breaking a promise she made to Futoshi to stay together, much to Futoshi's despair...