Prepare a small saucepan and heat sake and mirin to evaporate the alcohol.

Add soy sauce, sugar, minced garlic, and ginger to the saucepan. Simmer on low heat for 5 minutes until the sauce reduces to about 4 tbsp.

Slice pork belly into preferred sizes. Slightly freeze the meat beforehand for easier slicing.

Heat a pan and cook pork belly until golden brown. Avoid overcooking to maintain tenderness.

Clean the pan with a paper towel to remove excess grease. Pour half of the prepared sauce into the pan and adjust the amount to taste.

Simmer the pork belly in the sauce on low heat, flipping occasionally to coat evenly. Optionally, use a torch to add a smoky flavor.

Serve warm rice in a bowl and drizzle remaining sauce over it.