first, whack the dude in the first battle.
second, after you get our from the first town go back in and talk to the guy who is still limping on the ground
third, go up to north (second town) and trigger the event there...
fourth, the girl's family will request whether you could kill the wanted monster
fifth, accept the quest and go to the hunter office on the 2nd town for more info
sixth, go to the factory on the left and kill it
seventh, go back to town and retrieve your bike
eight, go to pentagon and trigger the event