1Wash 300g of Japanese short-grain rice thoroughly until water runs clear, then drain. Combine the washed Japanese short-grain rice with 360g of water in a rice cooker or heavy-bottomed pot and cook until fluffy.
2While the rice cooks, prepare the butadon sauce. In a small saucepan, combine 60g of Koikuchi soy sauce, 45g of mirin, 30g of sake, 15g of granulated sugar, and 60g of dashi stock. Heat over medium heat, stirring until the granulated sugar dissolves, then bring to a gentle simmer for 2 minutes and set aside.