Prepare Yudane by combining 50g of bread flour with 40ml of boiling water in a bowl. Mix well, cover, and let it rest at room temperature for 30 minutes, then refrigerate overnight.

On baking day, mix room temperature milk, sugar, and softened butter in a stand mixer. Sprinkle dry yeast and tear the Yudane into pieces, adding to the mixture.

Gradually incorporate remaining bread flour and salt, mixing on low speed until combined.

Knead the dough with a dough hook for 5 minutes on low speed, then increase to medium for 20 minutes, until smooth and elastic.

Place kneaded dough in a greased bowl, cover with a towel, and let rise in a warm spot for 45 to 60 minutes, until doubled in size.

Punch down the risen dough, divide into two pieces, shape into balls, and rest under a damp cloth for 20 minutes.

Roll each ball into a rectangle, fold tightly, and roll up to shape the loaf.

Place shaped dough in a greased loaf tin, cover with a damp cloth, and let rise for 30 minutes, until it fills the tin.

Preheat oven to 365°F (185°C). Bake the loaf for 25 to 30 minutes, until golden brown and sounds hollow when tapped.

Remove from oven, cool in tin for 10 minutes, then transfer to wire rack to cool completely before slicing.