01 - Pound chicken thighs to uniform 1/4-inch thickness. Season both sides generously with salt and pepper.
02 - Dredge each thigh in flour, shaking off excess. Dip into beaten egg mixed with milk, then press firmly into panko breadcrumbs to coat completely.
03 - Heat 1/2 inch vegetable oil in skillet over medium heat to 350°F. Fry chicken until golden brown and cooked through, approximately 3-4 minutes per side. Transfer to paper towels to drain. Slice into musubi-sized strips.
04 - Whisk together rice vinegar, sugar, and salt in small bowl until dissolved. Gently fold mixture into warm rice, being careful not to mash grains. Allow to cool slightly for easier handling.
05 - Combine tonkatsu sauce, soy sauce, and honey in small bowl. Whisk until smooth and well incorporated.
06 - Lay plastic wrap on flat surface. Place halved nori sheet shiny side down. With moistened hands, press 1/4 cup seasoned rice into compact rectangular shape in center of nori. Sprinkle with furikake if desired.
07 - Top rice base with chicken katsu slice. Drizzle lightly with sauce. Add thin layer of rice and press gently. Fold nori edges tightly around filling using plastic wrap to compress. Let rest 2-3 minutes for nori to soften and seal before removing plastic.