First seen Day 101.
Though it was mentioned earlier by Redhead in Day 27 Sidestory : Redhead's POV.
A large, gray chicken-type monster.
Can make its lair in the general vicinity of the highway.
It's likely that it's not even able to harm a Skeleton Horse.
The Big Cocco, better known as a Misutenddo, is a small-fry monster that newbie adventurers tend to hunt for early level experience.