This is presumably the flash memory containing the game ROMs and menu program. It looks as if a larger sized chip was originally installed, and then replaced with a smaller one, and a form of adapter board created to avoid redesigning the PCB.

The chip has 080-92008012 on the adaptor board, and M5MLT157N1P JPN ENG-C 706208. I have tried Googling for this, but cannot find any more information.