The VR factor is a phenomenon in the story of Wild Arms 5 where the technologically and physically advanced race of the Veruni are becoming sick and dying at an increasing rate due to the biological differences between them and humans causing the planet Filgaia to reject them. The disease claimed a large number of lives, including that of Persephone's sister and both of Fereydoon's parents. The Baskar scientists in the story, alongside Professor Elvis, do thorough research into the condition to try and resolve it, determining that while possession of the Guardian Mediums can counteract the effect, the Veruni are unable to activate them. Towards the end of the story, they determine that the way to overcome the VR factor is for the Veruni and humans to accept each other, coexisting and living in peace.
In the original Japanese screenplay for the game, this effect was called the Ub component (Japanese:Ub成分, 「Unaccept Beruni 成分」)[1], and so it can be inferred that the adaptive English acronym "VR" stands for "Veruni Rejection".