In the bowl of a stand mixer whisk dry ingredients except matcha powder.
Add water, milk and tangzhong and knead until just combined. Cover with plastic wrap and let rest for 5 min.
Add butter and knead with hook attachment until smooth and elastic (about 10-15 minutes).
Divide dough into 1/3 and 2/3 portions. Shape the 2/3 piece into a ball and place into a greased bowl. Cover and set aside.
Add matcha powder to the remaining 1/3 dough and knead to combine. Cover and let rest until doubled in size (1h- 1h30).
Roll out plain dough into a 20x30cm rectangle. Roll out cacao dough into a 20x15cm rectangle. Place cacao dough over one half of plain dough and fold the remaining plain dough over.
Roll out into a 20×30 cm rectangle again. Cut dough cross wise and stack the two doughs. Roll out to combine. Repeat two more times
Cut dough into 3 equal stripes, lengthwise. Roll out each stripe into a rope and braid the 3 ropes together.
Fold ends under so that the bread fits the pan. Let rise for 1 h.
Preheat oven to 175C degrees and bake for 25 minutes. Brush with melted butter. Let cool down into the pan for 15 min then cool completely on a rack.