|Status: Alive, somewhere|
Seikou was designed by the eccentric scientist Hitomi Fujimoto, and originally intended to serve as a prototype of a new antivirus system. This system would "quarantine" any areas affected by the Maverick Virus, cutting them off from Seikou's systems beyond the bare minimum needed to function. This was meant to stop any infection from spreading.
However, in one combat, Seikou became infected. While the antivirus seemed to function perfectly, a system contradiction lead to its failure. An emergency system designed to reroute functions to neccessary areas in low-power conditions ended up leeching power from the antivirus, causing the infection to spread quickly through Seikou's systems.
After a period of massacre, the antivirus managed to successfully recontain the virus. However, Seikou was mentally traumatized by what he had done, and fled to the Cleft to escape his past.
Once there, all seemed to go well. The virus seemed to be dormant at last, and Seikou quickly found a friend in Variance, who helped Seikou get into the Cleft variant of the Maverick Hunters. All seemed to be going well until a mission to the strange Magitek Factory wounded Seikou badly - causing the antivirus to fail once again.
While Seikou recovered from this, the event did not go unwitnessed - Vice decided to use Seikou against both himself and Variance. Over the next few days, Seikou was constantly hounded by the Maverick, and eventually was even kidnapped. During the kidnapping, Vice managed to break Seikou's mental defences by lying about Variance and a girl Seikou had met named Aura - claiming they were both dead. Seikou snapped yet again, although Aura and Variance succeeded in helping him. The incident left only two permanent signs: Variance now carried a minor strain of the Virus, and Seikou now wielded a black saber given to him by Vice instead of his characteristic polearm.
For a while, everything seemed to be back to normal. Seikou fell in love with Aura, and the two started a deep relationship, bonding quickly. The Hunters also went well, with neither Variance's or Seikou's strains of the Virus making themselves visible.
Until, of course, Vice screwed it up again. First he framed Aura for a massacre in Cosmo Canyon, and nearly succeeded in breaking Seikou until Variance disproved Aura's involvement. Then he actually went on a massacre in Rocket Town, and admitted this one to the Hunters. Seikou, witnessing the crime scene, finally gave up on protecting anyone - and deleted the Antivirus.
The infected Seikou posed as the real one for some time, even informing Variance in hysterical tones of a murder he had caused. However, he slipped up a few too many times and was imprisoned, with no seeming hope of recovery. Aura was eventually the one to help him as she left to find herself, providing him with a means of suppressing the Virus.
((there is more but i am tired of writing and confused about the order of events so later >>; ))
More recently, he's busy raising his and Aura's child while his Hetereosexual Life Partner Variance is busy being dead.