Are we sure that it was a pinball machine? Recently I travelled to Takamatsu and in the docks area they had a store with tonnes of old school retro Japanese arcade and pachinko machines. The store had a strict no photos policy but you can find a couple of pics on Google maps.
In the back of the store they had a few partially covered up machines and I swear I saw a spiral on the side of one of them. The old style pachinko machines look a lot like pinball machines. Is it possible that we're looking in the wrong place or this was just different prototype entirely?
