Wash and peel the Daikon radish. Cut into 3cm thick.
Place the cut daikon and pork in a pressure cooker. Add water to just cover the daikon and pork.
Add rice to the pressure cooker, lock the lid and cook over high heat.
When the pressure indicator pin rises, turn the heat down to low and cook for 15 minutes.
Turn the heat off and allow the pressure to release naturally.
Remove the pork and daikon radish from the pressure cooker.
In a different pot, add 1/2 cup of the water the pork belly was cooked in, 1/2 cup sake, 3 tbs soy sauce, 1 tbs mirin, 2 tbs dark muscovado sugar, and sliced ginger.
Place the pork and daikon (removed from the pressure cooker) into the pot and bring to simmer.
Simmer the daikon and pork belly for about 20 minutes with a small lid (called Otoshibuta or a drop lid) resting directly on the daikon and pork belly.
When the liquid sauce reduces to about 1/2, turn the heat off and garnish with chopped green shallots to serve.