This is PSOBB Episode 4 monsters that usually appears in either the Crater or the Desert. To tell you the truth lots of players are getting frustrated with this creature all because it swoops down a lot and shoots beams (like Nano Dragon).
Also there was a Rare Monster of it called "Pazuzu", it was colored in green and a little orange. Most often Rare Monsters gives off high EXP and maybe a Rare Item as well. If you're lucky enough... you may as well consider the most luckiest person in game.
NOTE: It's useless to use Close-Combat Weapons unless you get near, under the Zu. It will come down and shoot fire balls. Or use guns and maybe some Techniques if you are a Force. As for Androids use Frozen Traps to stop and freeze it you will likely to hit it with your best shot.