I've been test baking bread this week. I've wanted to try Japanese milk bread for a long time and finally baked my own on Monday. It was always described as very soft and fluffy bread that had excellent keeping qualities so I thought it would be a good bread to have in my repertoire of bakes.
The bread has something in common with sour dough in that you prepare a starter before you bake and include it with the ingredients. This starter is called TangZhong, a mixture of flour, milk and water, cooked and allowed to cool to room temperature. It helps the bread retain moisture and is the reason it stays fresh longer. This is the recipe I followed.