I own a classic Mamiya - The Mamiya Six. Not Mamiya 6, but Mamiya Six.
It is a medium format camera, and has the distinction of being the first Japanese camera made for export after WWII. My particular model was produced during the American occupation of Japan. Interestingly, it is stamped "Made in Occupied Japan" on the bottom.
The Mamiya Six is similar in size other contemporary folding cameras, and has an odd focusing system - the lens doesn't focus and the lens stage doesn't move, but the film plane is moved instead. This theoretically allows the lens to maintain the optimum element spacing. The camera has some other nice features, including a flash-sync, double exposure prevention, and auto-stop winding. As its name suggests, it takes 6cm x 6cm photographs on 120 size roll film.
There also exists a close-up accessory lens for this camera, which I don't own...