In a small mixing bowl, dissolve yeast and sugar in warm water. Let stand about 10 minutes. Heat the milk in a small saucepan until it bubbles, then remove from heat. Add the butter and stir until melted; let cool until lukewarm. In a large mixing bowl, combine the yeast mixture with the cooled milk, matcha, butter, egg, 2 cups flour and salt. Beat well to combine. Add the remaining flour, 1/2 cup at a time, stirring well after each addition. When the dough has pulled together, turn it out onto a lightly floured surface and knead until smooth and supple, about 8 minutes. Cover dough and let rest for 10 minutes. Cut into 6 pieces. Shape each piece into a turtle, then cover and rest for 20 minutes. Score the backs of each turtle to make a shell pattern. Bake at 400 for 12-15 minutes. Enjoy!