After being rescued from the shipwreck, the team struggle to deal with the loss of Three. Kichi and Marthea find themselves separated and are rescued by a stranger named Ashigaru. And Naoki finds himself facing an RTT impostor.
Naoki, defeated by the RTT imposter and left for dead, is rescued by a kind family and discovers a shocking secret his friends have kept from him. Meanwhile, Tokichi and Marthea search for a supposed hidden RTT base on the island.
Naoki, having discovered the truth about his past, fights his doppelganger whilst his sister races to complete "Project Four" in time to stop the invasion.