Preheat oven to 500 degrees F. Pat skin and cavity of chicken dry with paper towels. Sprinkle 2 tablespoons Japanese 7 spice all over outside and inside cavity of chicken. Place on a small rack in a roasting pan, breast side down. Insert 2 orange wedges into cavity. Roast for 20 minutes.
Turn chicken breast side up. Arrange carrots and bok choy around rack in roasting pan. Drizzle vegetables with olive oil and season with salt.
Reduce oven to 350 degrees F. Roast for 1 hour more or until an instant-read thermometer inserted in the thickest part of the thigh registers at least 170 degrees F. Brush with 1 tablespoon butter during the last 5 minutes of roasting. Remove oranges from cavity and squeeze juices into roasting pan. Remove chicken and vegetables to a platter. Sprinkle vegetables with additional Japanese 7 Spice. Cover and let stand 15 minutes.
Meanwhile, add chicken broth to hot roasting pan. Cook and stir over medium-high heat, scraping up browned bits in bottom of pan. Bring to boiling. Boil, uncovered, for about 8 minutes or until liquid is reduced to 1/2 cup. Remove from heat; whisk in sesame oil.
Carve chicken and serve with vegetables and sauce. Sprinkle with fresh herbs. Serve with remaining orange wedges.
Japanese 7 Spice Mix
Shake everything together in a small jar, cover and store in a cool, dark place for up to 6 months.