Tails!?

Several years have passed since Goku's and Vegeta's first meeting- and their first battle. Something like hatred, yet very akin to a twisted form of friendship, is very powerful between the two Saiyans. But when their tails suddenly grow back with no warning and seemingly no cause, Bulma finds herself with a very dangerous beast roaming her house by night, howling and calling for hours on end for what she only guess to be another of its kind...