For all of you who are having an intensly difficult time slaying or repelling the Yian Garuga in the urgent quest, there's a simple glitch that will get you pass the mission.
First, empty your inventory into your box at your house. Buy a spiderweb from the lady at the vegetable stand outside your house and start the quest. Go to area 7 where the veggie elder is (short old guy with a cane). Talk to him by pressing the O button. He'll trade you a special mushroom for your spiderweb. Now just stand in area 7 and wait for the 20 min. time limit to run out and you'll receive the message "you won the battle" and the quest will be cleared.