Place the soy sauce, mirin, 4 tablespoons of the sugar, 4 tablespoons of the peanut oil, sesame oil, garlic, ginger, and green onions in a blender and process on low for 1 minute, or until smooth. Transfer half of the marinade to a large resealable plastic food storage bag, add the drummettes, and seal the bag. Turn the bag so that the drummettes are well coated, and refrigerate for at least 3 hours and up to overnight, turning occasionally.
Preheat the oven to 425 degrees F.
Drain the drummettes and discard the marinade. Line a large baking sheet with aluminum foil and lightly oil the foil using the remaining teaspoon of oil. Place the drummettes on the baking sheet and bake until browned around the edges and cooked through, about 20 minutes. When the drummettes are done, remove them from the oven and transfer the baking sheet to a cooling rack while you prepare the glaze.
Place the remaining marinade in a medium saucepan and add the remaining 2 tablespoons of sugar and the crushed red pepper. Bring to a boil over high heat and cook until thickened enough to coat the back of a spoon, 4 to 5 minutes. Transfer the glaze to a heatproof bowl, add the hot chicken drummettes, and toss until the drummettes are thoroughly coated. Transfer to a serving platter, garnish with the cilantro, and serve