Ren Karatachi is from the Karatachi Family, And suffers from mass hysteria. From Ren's special form of mass hysteria, the sight, smell, or taste of blood leads him to enter a blood lust frenzy where his eyes dilate, followed by an uncontrollable urge to destroy everything in sight. This effect lasts until he is no longer able to sense blood around. At a young age, Ren's condition was diagnosed as Ren suffered from insanity hearing voices in his head he constantly argued with. As he grew older, the voices in Ren's head no longer seemed to argue but only help him as a 6th sense. By creating a cloud of chakra around himself that is invisible to the naked eye, Ren's 'inner voices' are able to detect danger around him and locate things similar to the byakugan, but have very poor descriptions of what is around. Though the voices originally only began when Ren entered a frenzy state, The voices blend in with his thoughts whenever he unsheathes his blade.