mix all the ingredients besides the butter in a stand mixer at low speed (I used a bread machine) for about 5~8 minutes until it's well combined*
use a damp towel to cover the container of the dough for 20 minutes (autolyse method)
add butter and mix from low speed to high speed for about 8~10 minutes (until you can stretch a corner of the dough for at least 4 centimeters)
take the dough out and roll it into a smooth ball. Put it in a bowl with a little bit of oil to prevent sticking.
ferment the dough for 1 hour at 30°C or just put it in an oven with the light on
the dough should be at least double-sized now. Take it out and divide it into 3 pieces. Rest them for 20 minutes with a damp towel on.
spread some flour on the counter and roll each dough into a rectangle shape (the length should be a little bit shorter than your mode). Put the adzuki bean paste on (about 75g for each dough).
roll the edges together and try not to spill the bean paste out
stick the top of the doughs together and braid them together, also stick the bottom in the end. (You can see the photos above)
with the help of a spatula, put the dough into your baking mode carefully.
second fermentation for 1 hour, or until the dough reaches 90% in the mode.
preheat your oven to 190°C
bake the bread for 35 ~ 40 minutes, cover a foil when it is golden on the top (about 20 minutes)
take it out and cool it down before serving