Yamato believes that the assailants were not grave robbers but were after Sora. He decides to appoint Sora to Team Kakashi as a temporary stand-in for the injured Sai.
If you don't...
something terrible will happen.
فإن لم تفعل... سيحدثُ أمرٌ فظيع
Si no lo haces, pasará algo terrible.
Si no lo haces, pasará algo terrible.
Se você não se comportar,
 algo horrível pode acontecer.
Иначе случится нечто страшное.