whomever is worthy. It's appearance is that of the top half a dragon's head with a clawed hand at each side. When its jaw opens, it is able to breath out a continuous fire. This fire is harmless to those who are "worthy", and to those not, "inexplicable pain". The one disputed case is when Leo put his hand to the fire, but it burned out, and he was left with no weapon. This could be because Leo was unworthy and Juto was only trying to scare the Acolytes, or something else.
"Those who are worthy will find what they seek. Those who aren't, inexplicable pain!"
— Juto-Shisho