Prepare wooden skewers by soaking in water for 30 minutes. Or use metal skewers.
In a large bowl, combine the soy sauce, honey, mirin, water, sugar and garlic. Add the chicken to the bowl and toss to coat well.
Transfer the chicken and marinade to a zip lock bag and refrigerate for at least 30 minutes and up to 24 hours.
Preheat the grill to medium high.
Thread the chicken onto the wooden or metal skewers. Grill the skewers for 5 minutes per side or until the chicken has a good char.
Remove the skewers from the grill and serve immediately.