After walking through the desert to get past a traffic jam, you finally reach Fourside.
Buy the Broken Gadget
Go to the junk shop in northeast Fourside and buy the Broken Gadget. This turns into a stronger weapon for Jeff if he repairs it overnight, which he can do when his IQ becomes 34 or greater.
Help the Runaway Five
Go to the Topolla Theater and buy a ticket. Go into the office of Miss Fake, the theater manager. Talk to her to find out that the Runaway Five are stuck in another phony contract. Go into the theater and watch their show, then talk to them backstage.
Get Some Pictures Taken
Walk up the steps of the Fourside Museum to make the Photo Man appear.
Go between the two trees that are between the Monotoli Building and the Department Store to make the Photo Man appear.
Back to the Miners' Shack
Go back to the miner's house in the desert. To reach it, you can go north from the eastern tunnel of the desert, then go west. If you gave food to the miner earlier, and if you spoke to Miss Fake at the Topolla Theater, you will discover that the miner has made a lot of progress. (If you didn't give him food, give him some now, then leave the area and come back.) However, he can't continue because of the monsters in the mine.
Clear Out the Mine
Go north from the entrance of the mine until you find a ladder. Go down it, then go to the left. Go into the alcove in the north to battle a Guardian Digger. Use Flash on it, then use your strongest PSI attacks. If Jeff has the Shield Killer, he can use it to get rid of the Guardian Digger's Shield α, which will deflect physical attacks back at you. After that, Jeff can use Bottle Rockets.
After you kill the Guardian Digger, you can open the gift box that it was guarding to get an IQ Capsule.
Then go to the left and go up the ladder. Go south until you can't go any farther south, then go northwest. Open the gift box along the way to get a Big Bottle Rocket (or ignore it, because you can come back later when there are no more monsters in the mine).
Continue going north, then go left when you can. You will find some Exit Mice. You should consider taking an Exit Mouse or two so you can leave the cave if you are too low on PP or HP.
Open the gift boxes near the Exit Mice to get a Picnic Lunch and a Croissant.
Then go south from the Exit Mouse area. You can open the chest along the way to get a Bomb. Continue on this path and you will reach a Guardian Digger. Use the same strategy as before. Then open the gift boxes that it was guarding to get a Luck Capsule and a Platinum Band.
Go back to the Exit Mouse area and keep going north. You can go to the right when the path splits if you want to get a Secret Herb. Then go back to the path and go north to find another Guardian Digger. Battle it the same way as the other two. Afterward, open the nearby chest to get a Guts Capsule.
Go back to the Exit Mouse area, and this time, go west, then south when the path splits. You can go down the ladder to find a Super Bomb. Then go back up the ladder, and go west to find another Guardian Digger. Fight it the same way as all the others. Then open the nearby gift box to get a PSI Caramel.
Next, go back the way you came, and go north when the path splits. At the next split, you can go right to get a Teddy Bear. Then go back to the path and go north. Go down the ladder there, then go east. You can go south into a small area and open the gift box to get a Calorie Stick.
Then keep going east to find the final Guardian Digger. Use the same strategy as always. Then open the gift box to get a Coin of Defense.
Now that you have defeated all five Guardian Diggers, there are no more monsters in the gold mine. You are free to explore and pick up any gift box items that you might have missed.
Afterward, leave the cave. You can talk to the miner near the entrance. When you are ready, go back to Fourside. The Photo Man will take your picture as you leave the mine.