For the best results, reheat leftover pork in either an air fryer or in a hot oven. Both of these methods will keep the meat tender and juicy while crisping up the panko crust. If using an air fryer, about 5 minutes at 350 degrees F should do the trick. For the oven, preheat to about 425 degrees F. Arrange your pork katsu on a baking sheet and cook for 12-15 minutes, until warm and crispy.