Gale Wind

Gale Wind (疾風のウィンド, Hayate no uindo) is a ninja from Sonic's ninja village from 37th graduating class like Hellfire Flame. He and Hellfire Flame joined the Monster Association some time in the past to rule the world.

Appearance
Gale Wind is a tall young man with a muscular physique and long, wavy light-colored hair and has a marking under his right eye.

His attire consist of a tight fitting shirt, white hakama pants with black trimming, white sash and black arm warmers. Gale Wind also has metal bands around his biceps and neck.

When he transforms into a monster, his teeth become sharp, his skin gains black marking and his eyes began to twist like a lizard.

Personality
Gale Wind is shown to be quite sadistic, but playful and polite toward his opponent. He is a strong believer in the superiority of monster over human so he choose to join the Monster Association to rule the world.

Monster Association Arc
Gale Wind and Hellfire Flame attack Speed-o'-Sound Sonic in a forest as a form of skinship and introduce themselves as Sonic's senior form their ninja village. After some discussing, Gale Wind and Hellfire Flame invite Sonic to join the Monster Association to further their goal to become rulers of the World. Gale Wind reveals their plan to attack the Hero Association, more specifically killing Flashy Flash and asks Sonic's help to distract the other heroes. When Sonic refuses, Gale Wind transforms into a monster and demonstrates his speed, shocking Sonic and explains the process of the transformation. They then offer a Monster Cell to Sonic and leave.

He and Hellfire Flame are present at Gyoro Gyoro's speech.

Abilities and Powers
Gale Wind comes from the same ninja village as Sonic and is a graduated ninja, so he is immensely strong.

Physical Abilities
Immense Speed and Reflexes: He is shown to have superhuman speed that even surpasses Sonic's, as he demonstrates his speed to Sonic, who couldn't even see him.

Transformation: Gale Wind can change into his monster form and revert back to his human form freely. According to himself, he achieved this through ninjutsu training.

Trivia

 * In the webcomic, there is a monster named Gale with a partner named Hellfire who also tries to kill Flashy Flash. Whether or not this is the same character is unknown.