It's pretty common for Akitas to nip and bite, especially when they are puppies and still teething. While Bowser might not think much more of biting than as a normal part of play, his sharp teeth can, in fact, be quite painful. If you don't break this habit while he is a puppy, by the time he gets to be an adult, his bites can cause serious injury. Bear in mind, while teething puppies will chew on just about anything they can get their teeth on. The chewing helps to relieve his pain in much the same way it helps a teething baby.
Your first job is to discover why Bowser is biting. In young pups, it is usually because they are teething or playing. In the wild, they cut their teeth biting and chewing on anything they can find and will learn to control play biting with the help of their litter mates. But in your home, this is just not acceptable behavior. In an older dog, biting is part of the hunt and survival, but again this is not necessary in a domesticated situation. Bear in mind, you are trying to train your dog to do something that is completely against his nature. Be patient, stay calm and keep working with him until he finally stops this unpleasant behavior.
While you will need a few supplies to use during training, the most important of them you cannot buy. These are time and patience. You need to make sure you set aside time every day for at least one training session until Bowser finally learns not to bite. It will help to have a few supplies handy as well:
Keep working with Bowser, don't give up if he seems like he isn't getting the idea. This is the time to try a little harder--he will figure out, it just might take a little extra time.