...the pet and the partner
Leon the Camaleont, mysterious as his owner Reborn. He is 25 cm long, he has 0.5kg and he was born in Italy. There are just few thing we know about this small green thing. He can change shape in to the weapon of choce of his owner, he creates the bulletts, and the more that Reborn's student grows and learns, less bullets he creates. While the student is progressing, his tail falls off, he becomes unstable in his shape-shifting, and he isn't able to create bullets anymore, till he finally creates the special item for Reborn's student (in Tsuna's case that would be the gloves)
The bullets created by Leon are the Dying Will bullets, that when used on a person, use the person's pressure that the person is facing during a crysis and externally remove the person's body limiters. Then increses the person's streinght and renwed confidence to fulffill his dying will - ergo the last tought the person regretted fefore being shot. In the begining it's said that they last for 5 minutes, but then later it seems the dying will flame goes away when the regret is accomplished.