The 4th colour for Shibumi will officially be Yellow. There are no Shibumi games that use this 4th colour yet, so maybe yours will be the first!
Price for a set of 16 phenolic yellow balls (25 mm. For Shibumi Samurai and Shogun editions): 32 € ($
Price for a set of 16 plastic yellow balls (19 mm. For Shibumi Ninja edition): 5 € ($
If you wish to place an order, please contact me here.