Mix the yeast, water, and sugar. Cover with wet cloth and let rise for 10 minutes.
Add the flour, salt, and powdered milk. Knead until not sticky. Cover with wet cloth and let rise for 10 minutes.
Add butter and knead. Cover with wet cloth and let rise for 1.5-2 hours.
Matcha bread dough
Mix everything together. Cover with wet cloth and let rise at the same time as the white bread dough.
Split both the white bread dough and matcha bread dough into thirds.
For each piece of dough, roll into rectangle shape, making the white bread dough pieces slightly larger than the matcha bread dough pieces.
Lay out the white bread dough pieces; on each one, place one matcha bread dough piece. You should have 3 pieces total.
For each piece, roll into a tube.
You will have three tubes. Place the three tubes into a loaf pan (the flat circular parts of the tubes should be touching each other, and the short side of the loaf pan).
Cover with wet cloth, let rise until doubled in size.
Bake at 350 F for 10 minutes.
Brush top with egg wash (mixture of egg yolk and water).
Take top edge, fold to meet the bottom edge (folding dough in half). Then take the right edge, fold to meet the left edge. Turn the dough 180 degrees. Repeat.
Repeat step 3 twice.
Repeat steps 2-4 twice.
Once the dough has doubled in size, place in round baking tray. Spray top of bread with water.
Bake at 400 F for 20 minutes, placing the bread on the top rack. Also place a baking dish with water on the bottom rack.