Soak bamboo skewers in cold water for 10 minutes, then drain. Place soy sauce, sake, sugar, ginger and chives in a screw-top jar and shake well to mix.
Trim chicken breasts of any fat and membranes and cut into bite-sized cubes, about 1 1/2 inches. Place chicken cubes in a shallow glass or ceramic dish, pour marinade over cubes, cover and refrigerate for 1 hour.
Preheat a stovetop grill pan, broiler (grill), or barbecue.
Cut scallions into 2-inch lengths. Drain chicken, and thread cubes onto skewers alternately with scallions. Brush chicken and scallions with olive oil and cook until golden, about 5 minutes per side.
Serve hot with soy sauce for dipping.
(Can be assembled 2 hours ahead. Then cook and serve.)
Recipe courtesy of Hors d'Oeuvres by Vicki Liley, Periplus Editions/Tuttle Publishing