In a mixing bowl, combine 1 cup of Umi All Purpose Home Baking Flour, 1 teaspoon of baking soda, 1/2 teaspoon of salt, and 1/2 cup of sugar. In another bowl, whisk together 1 egg, 1/4 cup of melted butter, and 1/2 cup of milk. Gradually add the wet mixture to the dry ingredients, stirring until a smooth batter forms. Pour the batter into a greased 8×8-inch baking pan and bake in a preheated oven at 350°F (175°C) for 25-30 minutes or until a toothpick inserted into the center comes out clean. Let it cool, then slice into squares, and enjoy your homemade Umi All Purpose Home Baking Flour cake!