01 - Pound chicken thighs to even 1/4-inch thickness. Season both sides generously with salt and pepper.
02 - Dredge seasoned chicken in flour, shaking off excess. Dip into beaten egg blended with milk, then press firmly into panko crumbs to coat completely.
03 - Heat 1/2 inch vegetable oil in skillet over medium heat to 350°F. Fry chicken 3-4 minutes per side until deep golden brown and internal temperature reaches 165°F. Drain on paper towels and slice into musubi-width strips.
04 - Whisk rice vinegar, sugar, and salt until dissolved. Gently fold into warm cooked rice. Let cool to room temperature.
05 - Combine tonkatsu sauce, soy sauce, and honey in small bowl. Whisk until smooth and well blended.
06 - Lay plastic wrap on flat surface. Place halved nori sheet shiny side down. With damp hands, press 1/4 cup seasoned rice into compact rectangle in nori center. Sprinkle with furikake if desired.
07 - Place chicken katsu slice over rice. Drizzle lightly with sauce. Add thin rice layer and press gently. Fold nori ends tightly around filling. Use plastic wrap to compress into rectangular block. Let rest 2-3 minutes for nori to soften.
08 - Remove plastic wrap. Repeat with remaining ingredients to form 8 musubi. Serve immediately with extra sauce or wrap tightly for portable meals.