Fuyuki grew up on Iinowae and spent most of his childhood moving from place to place, thanks to his dad's varying careers. Due to being an Irregular and frequently fearing for his life, he lived in the background. His dad was an alcoholic and workaholic, so Fuyuki practically raised himself since his mother was out of the picture. He met Hiro when he was eight and once more in high school, where they bonded over similar ideals. They developed a plan to flee Earth and built a military-grade ship, but were spotted around Castor's Asteroid Belt by the Iinowaen Intergalactic Transportation Agency and shot down. Their ship crashed onto Castor, leaving Fuyuki paralyzed and Hiro nowhere to be found.

Despite being found by Xibagantans, Fuyuki quickly took his own life after seeing that Hiro was returned to Iinowae and executed on live TV.