Mustain plays the guitar and is know by other teams to be a playboy. He was the one who found an unconscious Melrose when the Dark Air first appeared. Mustain is currently a traveling companion of Melrose, Shenandoah, Emika, and Forest Freelander.
Mustain has past-shoulder length black hair which he normally ties up. Mustain also normally wears glasses, though he takes them off when in a battle. Most of the time, he wears a long coat. When he goes to town, Mustain sometimes disguises himself in outfits ranging from just a fake mustache to a full mariachi outfit.
Mustain normally seems aloof, but during battle he can get serious as well. Also, he is known for being a playboy and often refers to himself as an "ajussi" when talking with women. He has a confident personality and a will to achieve what he wants. Mustain is a cunning man who can abandon his comrades yet caring enough to help them when they are in desperate need.
- Buffer: As a buffer, Mustain has reach the level of Grand Master for he's capable of casting both defense and offensive buff a the same time. Allowing him to create a barrier to protect himself while buffing his team.
- Guitar: Mustain uses a guitar as his tool to buff his teammates. And sometimes, to make money or draw people to him.
- F*cking Man: An offensive attack that create a sound shock wave that can shatter glass and make his enemy faint if they are hit by its full blast.
- Gazelle Walk: An offensive buff that increase the speed of his team.
- Weapon Shock Absorbed: Increase the durability of his team's weapon, making it able to withstand heavy impact.
Long before the start of the story, Dave was only a fledgling. An unknown musician without a shred to his name. That is until he joined up with Dio of Metal Maul and made a name for himself while honing his skills along the way. After staying with Metal Maul for sometime, he decided to break away from them for reasons not told to the audience.
After breaking away, he became a wanderer doing what he want and playing around with girls. He's especially played with all of the member in Team Night Wish and even Orien Shi from Team Sonic Boom himself. Many years of playboy and deceit lead Dave to become a lone wanderer with a job of escorting ladies and protecting them from danger. That is when our story begin.
While making his way across the Titan Mountain Range south of Chattanooga, Mustain came upon an unknown injured boy lying unconscious on the ground. And from a distant, Mustain witness a pillar made of blue air. After that event, Blue Air became none existing in the world. The Age of Dark Air is dawn.
Upon recovering the boy, Dave did his best to care the boy back to health. After 3 years, the boy made a full recover and told Dave his name which was Melrose Silvringtinker. He then told Dave all about the event that unfold the night of Dark Air. Knowing the truth, Dave decides to help the boy. Or rather, he decided to make use of the boy in order to fulfill his curiosity and role of the events unfolding that will ultimately shake their world.
- Mustain is a tribute to thrash metal guitarist Dave Mustaine of Megadeth.