Heat butter in medium-high skillet.
Sear 6 chicken thighs on each side for four minutes.
Reduce heat to medium.
Cook 2 tbsp butter and 6 cloves thinly sliced garlic for 2 minutes.
Add 1/2 cup (2 tsp rice vinegar, remainder mirin).
Reduce for 2 minutes.
Increase to medium-high.
Cook 2/3 chicken broth and 3 tbsp butter until butter is melted.
Add 2 tsp soy sauce and 5 tbsp yuzu juice.
Return chicken to sauce.
Cover and cook each side 5 minutes.
Add 3 scallions