Gather all the ingredients.
Optional Brine - In a mixing bowl, add 2 cups of water and 1 tbsp of salt. Add chicken and brine for 1 hour. Note - be careful not to over brine, otherwise it will come out too salty.
Soak wooden skewers in water for at least 5 minutes.
Grate garlic and set aside.
In a stove top pot, add all the ingredients for the sauce, Soy Sauce, Japanese sake, water, sweetener, Bonito Flakes, and grated garlic and bring to boil. Once boiling, reduce to simmer heat and let the sauce simmer for 2-4 minutes or until slightly reduced. Once reduced, strain sauce with a strainer and make sure to squeeze/press any excess sauce from the Bonito Flakes. Split the sauce into to 2 bowls, one for basting and another has a dipping/drizzling sauce.
Cut green onions into 1 inch pieces and set aside.
Cut chicken into 1/2 x 1/2 cube size bites and set aside.
Skewer chicken loosely (do not pack in tight). Use 2-3 pieces of chicken for every piece of green onion as picture shown.
Generously baste yakitori chicken skewer with sauce from step 5) and transfer to an Air Fryer. Cook for 4-5 minutes @ 390F, rotate the skewers and generously baste skewers again. Cook for another 6-8 minutes @ 390F until browned and internal temp reaches 165F. Once done, transfer to a serving plate, sprinkle optional Toasted Sesame Seed, and drizzle reserved sauce. Enjoy!