After a humiliating defeat, Isamu (the younger brother of Wataru Kazama) quits rugby and stumbles upon the Nebula House, a rent house, where its residents invited him as their newest housemate/co-tenant. Isamu soon learns that they are aliens in disguise, but decided not to further report at Xio, witnessing them not as a threat. However, when Halky's Samekujira, Jolly appeared to reunite with its master, this attracts the attention of a crime network, Dark Star Cluster. The Nebula House residents challenged them in a rugby match over Jolly's ownership. The house resident wins thanks to Isamu's coaching since the past three days and his renewed spirit but the Dark Star Cluster enlarge and rampages after being unable to accept defeat before being sent back to space by Ultraman X. In the end, Isamu rejoins his rugby team as the next championship takes place in London, England.