Matcha Mochi with Sweet Bean Filling

Name: Matcha Mochi with Sweet Bean Filling
Ingredients: ¼ cup (60 g) dried white navy beans; 1 Tbsp. plus 1½ tsp. (25 g) granulated sugar; 2 tsp. (7 g) light brown sugar; Pinch of kosher salt; ½ cup (60 g) shiratamako (mid-grade rice flour); ½ cup plus 1 Tbsp. (120 g) granulated sugar; ¾ cup (100 g) jyoushinko (high-grade rice flour), plus more for dusting; 2 ½ tsp. matcha powder, or substitute ground cinnamon; Kinako, for dusting (optional); Fresh or dried edible flowers, for garnish (optional)