Wash the Japanese sweet potatoes.

In a large mixing bowl, toss the sweet potato pieces with a small amount of vegetable oil or use a cooking spray. This helps the potatoes crisp up during the air-frying process. Ensure the sweet potatoes are coated evenly with the oil. This step is important for achieving a delicious flavor in every bite.

Preheat your air fryer to 400°F. Different models may have varied settings, so check your manual for the best results.

Place the marinated sweet potatoes in the air fryer basket in a single layer. Avoid overcrowding for optimal crispiness.

Cook the sweet potatoes in the air fryer until they achieve a crispy exterior, about 40 minutes. Periodically check and shake the basket to ensure even cooking. Check the sweet potatoes for doneness after 40 minutes. They should be tender on the inside and crispy on the outside. You can continue cooking for an additional 5-10 minutes if needed. (The cooking time may vary based on your air fryer model and the size of the sweet potato.)

Once done, remove them from the air fryer. Allow them to cool for a few minutes before serving. Enjoy!