This system is also known as:
The VMU is like a memory card for the Dreamcast (holds 200 memory blocks) but it can do much more than just save your game data. It has its own black and white LCD screen and buttons to allow self-contained play of VMU games. The screen also allows you to see secret information while playing Dreamcast games. You can download and modify characters from Dreamcast games and train them, etc (like a Tamagotchi or similar) , trade files with friends and share data between Sega Dreamcast and Naomi-based arcade games.
Platform: Sega Dreamcast Visual Memory Unit (VMU).