Shodai Nekketsu Kouha Kunio-kun/Game Centers

Nanba, Ebisuchou, and Koushien all feature Game Centers where you can play with a variety of machines. Each time you use a machine you use up a Prepaid Cash Card.

Knock Out
This is a strength test machine. It tells you your current level and exactly how much experience you need to earn to reach the next level. The name is perhaps a reference to the Punch-Out!! series.

Crane Game
The Crane Game can be used to acquire some of the rarest items in the game, although what you get is completely random and some items have no value. Virtually every item can be acquired by playing the Crane Game, but some items are so incredibly rare that even if you were to play via emulation and constantly reload to get the Prepaid Cash Card back it would take a very long time for any of the rarer items to show up.

Fortune Telling
Gives you a random fortune about how lucky the day is. This modifies your Luck attribute. Possible readings are:
 * "it's a little lucky": Luck +15
 * "it's really lucky": maximum Luck (255)
 * "it's unlucky": Luck -49
 * "it's really unlucky": Luck -113

Slot Machine
The Slot Machine is used to gain experience points. For some reason the Power Wrist does not double its payouts.

It plays like a standard slot machine; hit to start the wheels rolling, then hit  to stop each individual wheel (from left to right). Like a real slot machine, the bell is a wildcard; any matching pair of symbols can be used after it, but the experience gain is always the same regardless of what the payout is when you get three of that type.