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 filet to the bowl and toss to coat well.
Transfer the meat and marinade to a zip lock bag and refrigerate for at least 30 minutes.
Preheat the grill to medium high. Thread the beef onto the wooden or metal skewers.
Grill the skewers for 3 to 4 minutes per side or until the beef has a good char or has grill marks
Remove the skewers from the grill and allow the meat to rest for a few minutes before serving.