Pachinko
Takeichi Shomura, who ran an arcade in postwar Nagoya, redesigned the arrangement of pins around 1948. Until then, pins were spaced evenly in what was called bara-kugi. Shomura reduced the number of scoring pockets and used arrangements such as ten-kugi and yoroi-kugi to change how the balls flowed — this is the Shomura gauge. When he released his own machines the following year, a line three hundred meters long is said to have formed outside the shop every morning. This connects to another current on this map: he did not patent this breakthrough arrangement, and shared it with competitors instead. That is why pachinko spread across the country. Inventors usually miss out on the profit — Lizzie Magie of Monopoly, Ralph Baer of Pong, and the inventor of the QR code all stand in the same line as Takeichi Shomura (a primary source for why he did not file a patent could not be reached). There is one more thing worth noting. The system for exchanging balls for cash is called the three-shop system — it routes the exchange through three separate parties, the parlor, the exchange counter, and the wholesaler, so that it is not built as a single continuous act of gambling. It is said to have begun in 1961 with the Osaka method, devised by Toshie Mizushima, a former police officer. But this system is also said to break down if the exchange counter is tied to the parlor through capital or shared staff, so it is not a story with a clean, settled answer. As far as this map could confirm, I write it as operating in a gray zone.