The Oraga Stone is the source of energy to activate cyborgs, through combination of the train, to fight for evil or good. The only way to supply the energy to the stone is through sexual stimulation of women to orgasm. The M-77 Express was stolen by a professor who had betrayed the good guys to do his evil desires. The only way to stop him... ... the Sex Desire Express Zetsurinou

(Source: Anime News Network)