There are two types of safes you can find in Yakuza: Like a Dragon. The first, and more common of the two, are silvers safes. They typically have a decent item in them that you can use to refresh your party’s health and magic points, or it might be an equitable piece of armor that increases their stats. The others are gold safes. These contain higher quality items inside them, but they also don’t open unless you have a gold key to unlock them. Unfortunately, the game doesn’t tell you where to find these keys, and you can only find them from one location.
To get gold keys to unlock these safes, you need to speak to an arms dealer. The arms dealers are just like the other markets and vendors you find through Yokohama, although they’re a bit more hidden, even if you can see them on the map.
The easiest arms dealer to find in Yokohama is Fumie. You can find them at the bottom left of the map, at the corner of Sunrise Bridge and Sunrise Street. You’ll need to approach the door on the left side of the street to open it up and speak to Fumie.
The first thing she has available on her vendor are gold keys, and these sell for 10,000 Yen. If you have plenty of money, make sure to stock up on them as much as you can so you’ll always be prepared when you can encounter a gold safe.