An ex-SEGA employee revealed that he has owned an unreleased prototype of SEGA Pluto, which is a SEGA Saturn with a Netlink built in.
The ex-employee didn’t reveal his name, but he goes by the screen name “Super Magnetic” on the AssemblerGames forum. He explained that the prototype ended up on his desk after its original owner left the company. Later on, Super Magnetic left the company too, but he collected all the items on his desk, including the Pluto, in a box.
"This thing is a beast, and definitely the heaviest console I've ever held in my hands," Super Magnetic described the prototype. "The front features two controller ports, and on top you have a flip-top drive bay, a cart slot, a Power button, and the venerable Reset button. Note that the logo still says Saturn, so I'm guessing the Pluto codename was simply that, and they were thinking of branding it with the Saturn name ... The left and right sides feature beautiful-and-exotic vents, while the back is standard Saturn, save for the Netlink ports."
Super Magnetic was told that only two Pluto prototype units were ever built and that the one he has in number 2. The unit is still functional, but Super Magnetic couldn’t try it out with a game since he lives in Japan now and has no access to US Saturn titles
Nobody knows what happened to prototype unit number 1.
Make sure to check out SEGA Pluto in the gallery.