Wash the kabocha pumpkin thoroughly, remove the skin and seeds, then steam it.
Mash the steamed kabocha pumpkin.
Add bread flour, sugar, salt, and dry yeast, then knead the dough.
Add the mashed kabocha pumpkin, milk, and butter, and knead again.
Let the dough rise for the first proofing.
Shape the proofed dough.
Place the dough on a baking tray or oven pan for the second proofing.
Bake in a 180°C oven for 20 minutes.