I discussed this with several associates when I reached the Unicorn lands, and all of them repeated to me the story of the Ki-Rin Clan's journeys outside of Rokugan, and the stories of their encounter with large birds the locals referred to as "Roc." I've never seen the creatures again, so I cannot verify that these are in fact the creatures encountered by the Unicorn... although it is a strong possibility, considering their rarity in Rokugan. I have heard of two other encounters with them (one also on the Naga Plains, and the other at the fringe of the Forest of Shadow) but without a specimen to observe, there is no way to know for sure.
Earth 4
Water 4
Strength: 7
Fire 2
Agility: 5
Air 2
Reflexes: 4
Rolls When Attacking: 5k5
Rolls For Damage: 7k2 (beak), 5k2 (claw)
TN To Hit:20
Armor:None
Wounds Per Level: 8: -1; 16: -2; 24: -3; 32: Dead
Special Abilities: Flight: 75 ft. per second.