In the full form of Bijū, Roshi's consciousness is tightly intertwined with the proud and willful nature of Son Goku (or, alternatively, still suppressed by Obito or Kabuto), and this mixture creates a truly explosive temperament. Roshi was known as a stubborn person, whom even Ōnoki called hard-headed, and Son Goku adds to this a fierce reluctance to obey anyone. The beast cannot stand being called the faceless 'Four-Tails' and demands respect for its true name. Moreover, both Roshi and Son Goku share deep reverence for the Sage of Six Paths and his teachings. Observing Naruto, both — human and beast — with belated regret admit that they could have taken a different path if they had trusted each other. In battle, the full form is merciless and destructive: the beast smashes everything around using brute force. Beneath the layer of fury lies untapped kindness: precisely in this form Roshi finally decides to call Son by his name. Son Goku, despite his hatred for humans due to centuries of slavery, feels sympathy for those who, like Naruto, sincerely wish to save the tailed beasts. Having assumed the full form, Roshi is no longer merely a puppet — he is a duet of warrior and monkey king, whose voice sounds simultaneously as a threat and a confession.
