In a small saucepan, whisk together 100g of whole milk and 20g of bread flour over medium heat. Stir continuously until thickened.

In a large bowl, combine 360g of bread flour, 50g of sugar, 7g of yeast, and 5g of salt. Add cooled tangzhong, 1 egg, and 130g of milk.

Knead the mixture for about 10 minutes until smooth and elastic. Gradually incorporate 85g of softened unsalted butter.

Transfer to a lightly oiled bowl, cover, and let it rise in a warm place until doubled in size, about 90 minutes.

In a medium saucepan, combine 250g of frozen blueberries, 125g of sugar, and lemon juice over medium heat until thickened, about 10 minutes.

Roll out dough into a 16x16 inch square. Spread cooled blueberry filling evenly, roll tightly and slice into 9 pieces.

Arrange slices in a greased baking pan, cover, and proof for about 30-45 minutes.

Preheat oven to 350°F (180°C). Bake rolls for 25-30 minutes until golden brown and internal temperature reaches 200°F (95°C).

In a bowl, beat together 100g of cream cheese and 25g of butter until fluffy. Add 100g of powdered sugar, 1/4 tsp of vanilla paste, and a pinch of salt.

Drizzle cream cheese frosting over slightly cooled rolls. Serve warm or at room temperature.