Soak bamboo sticks in water for 30 minutes. After you start prepping the marinade and chicken, it will be around 30 minutes ◡̈
Grate ginger and garlic cloves and set aside.
To make the marinade, add grated ginger, grated garlic, soy sauce, mirin, water, sugar, and sake in a saucepan. Heat marinade on saucepan on medium heat for 7-8 minutes until the sauce starts bubbling and thickens. Cool marinade for 10 minutes.
Cut chicken thigh in 1 inch pieces. Make sure the marinade has cooled down and add ½ cup of the marinade to the chicken. Marinate for 15-30 minutes.
Cut green onions in 3 inch pieces. Get your skewer and add a piece of chicken then add 1-2 green onions. Repeat until the chicken reaches the end of the stick.
Cut parchment paper or foil to fit your air fryer (see above for baking instructions). Cook skewers for 3-4 minutes on 425 degrees Fahrenheit.
After 5 minutes, brush sauce on top. Flip over and brush sauce on the other side (both sides sauced!). Cook for 3-4 minutes at 450 degrees Fahrenheit until slightly charred.
To serve, brush some sauce at the top and garnish with sesame seeds.