Pre-soak 6-8 bamboo skewers.
Cut the chicken breasts into 1 inch pieces then put them in a mixing bowl.
Mix together the mirin, sake, soy and sugar until the sugar dissolves. Add the grated ginger and garlic.
Pour this over the chicken chunks and marinate for 30-60 minutes in the fridge if you can.
Heat a griddle pan or BBQ.
Thread the chicken onto the skewers and cook on a medium heat, turning every 30 seconds and brushing them with the marinade. Cook until golden and lightly charred.
Serve with Japanese-style relishes and salads.