Mishima

Mishima was a mortal who was given a tiny fraction of omnipotent powers by the rogue X in 2377. This gave him the status of omni'X, and he, like all other omni'X the next year, lost all given power after trying to create the X Continuum. (Star Trek: Phoenix-X: "Vengeance", "Avalon Battlefield, Part II")

The First X Continuum

Mishima was the only omni'X with an open communication with the rogue X, during their existence from 2377 to 2378. This was attributed to his special power, as every omni'X retained a unique powerful ability. In a way, his open communication had made him the highest ranking omni'X out of all; so much that, while in the X-Time bubble, he stood closest to where the rogue X resided and where the X Continuum was to be created.

While there, he fought Daniel, who wished to speak to the rogue X. Mishima saw the fighting itself as a way to increase his power so that he could join the X Continuum a lot faster. ("Avalon Battlefield, Part II")

Post Continuum

After the failure of the X Continuum, Mishima roamed the galaxy, trying to increase his reduced power. He hoped that with it, he, and others, would be able to create another X Continuum.

Unfortunately, a timeless war, brought on by the time-traveling Klokian began to escalate in 2380. Mishima joined forces with other omni'X in order to fight back every time-travel incursion and attack against omni'X they could find. This effort proved successful as they were able to over-power Klokian timeships, whenever possible. In fact, the Klokian took so much a beating, that Klokian, RaeLuna's father, was forced to take sanctuary aboard the Phoenix-X.

After a showdown, which proved that Captain Cell would not release Klokian to be slaughtered by Mishima and his group, Mishima and his group decided to move on to other Klokian. A decision to acquire a starship was also made. ("Power Levels")

The Second X Continuum

In 2383, the X Continuum was finally created by an omni'X named Rein. ("Broken Pieces")

It is not known what Mishima's reaction to this was.