Add Dashi, sugar, Sake, soy sauce and Mirin in a pan. Heat until boiling.

Add onion and cook for a minute at medium heat.

Add chicken pieces to the pan and cook until the meat is cooked through.

Beat egg in a small bowl and pour over the chicken and onion. Cover and cook for 30 seconds to 1 minute.

Slide egg and chicken with sauce over rice in a bowl. Sprinkle with green onion.