Cut the taro into pieces. Prepare the taro paste by steaming the taro pieces in a steamer over high heat for 10-15 minutes, or until completely cooked through. The pieces should break apart easily when done.
Add the sugar to the steamed taro. Using a masher, mash the taro into a smooth paste. Divide the paste into 12 equal portions and shape them into taro balls. Cover and set aside.
Prepare the dough by adding the milk, yeast, and sugar to the bowl of a stand mixer fitted with a dough hook. Stir the mixture with chopsticks or a spoon.
Add the flour to the yeast mixture. Turn on the mixer to speed 1 and knead the ingredients until a smooth dough forms, about 6 minutes. If the dough begins to climb up the dough hook, stop the mixer and push the dough back down into the bowl. Transfer the dough to a lightly greased surface, cover with plastic wrap, and let it rest for 5 minutes.
On a lightly floured surface, roll the dough with your hands until the surface is smooth. Divide the dough into 12 equal pieces and shape each piece into a ball. Roll out each dough ball on a lightly floured surface, then place a taro ball in the center of the dough.
Wrap the dough around the taro ball, pinching to seal tightly. Place each taro bun on a piece of pre-cut rectangular parchment paper. Repeat this process for the remaining dough and taro balls. Arrange the taro buns inside a steamer, leaving enough space between each bun to prevent sticking. Cover the steamer lid and let them rise for 60 minutes, or until the dough balls have expanded in size.
Add water to the bottom of the steamer and cover the lid tightly. Turn on high heat and steam the buns for 10-12 minutes, or until the taro buns are soft, puffy, and fluffy. Turn off the heat and serve the steamed taro buns warm.