Preheat oven to 425 degrees F. Line a baking sheet with parchment paper.

Combine soy sauce, sugar, sake, mirin, rice vinegar, cornstarch, water, garlic, and ginger in a medium sauce pot. Whisk together until well combined and bring to a simmer over low heat. Continue to simmer for 3-4 minutes or until thickened. Remove from heat and let cool slightly.

Brush teriyaki sauce on both sides of the chicken thighs. Lay chicken on prepared baking sheet and roast for 10 minutes. Flip chicken over and roast for another 10 minutes or until chicken is cooked and juices run clear. Remove from oven and keep warm.

Meanwhile, prepare miso broth. Heat 1 tablespoon oil in a large saucepot over medium-high heat. Add garlic, ginger, and the white ends of the scallions. Saute for 1-2 minutes or until aromatics. Add miso, ground sesame seeds, sake, and sugar, stirring to combine. Add dashi and bring to a boil. Reduce heat to low and simmer for 10 minutes. Season with salt, pepper, and MSG if using.

Cook ramen noodles according to directions on package. Slice chicken into strips.

Portion ramen noodles in bowls and ladle miso soup. Top with teriyaki chicken, soft boiled eggs, pickled ginger, nori, sesame seeds, and togarashi. Serve immediately.