In a large mixing bowl, whisk together the Mochiko flour, potato starch, eggs, sugar, soy sauce, Mirin, sliced scallions, minced garlic, and grated ginger until well blended.

Add the 2-inch strips of chicken thighs to the marinade, ensuring each piece is thoroughly coated. Cover the bowl with plastic wrap and refrigerate for at least 4 hours.

In a Dutch oven, pour enough oil to cover the bottom about 2 inches deep, and heat it to 350°F.

Carefully add coated chicken pieces in small batches to the hot oil and fry each batch for 4-5 minutes until golden brown and crispy.

Once golden and crispy, transfer the fried chicken to a cooling rack placed over a baking sheet.

Drizzle the spicy mayo and sprinkle furikake over the chicken before serving.