On Day 55, you will have a chance to only fight drones for 3,000 to 4,000 Neo Yen each. It is possible to make well over 3 million Neo Yen through those fights. At the town map screen, place the little "snowboarder" pointer over the garage area. Rotate the Right Analog-stick ten times in any direction to gain 1,000 Neo Yen. Note: You can only do this once per day.