How do you unlock oz from chrono days

When you get back to your own time, go to your house (The Emerald Apartments).Then click on your computer and then click Firecat. After you click fire cat, you will see that all the other androids to buy are SOLD OUT. So just click AI Series 02: Oz. But you are buying Oz, so you need to have 300$ in the game so you can buy him.