The Master (Japanese 師匠) is a retired Guild Knight that works in secret among the Monster Hunter world. He was the original leader of the Ace Hunters.
The Master is described to be a person that never loses his smile, no matter the situation. Though he has been scarred in battle and can keep a smile on his face, the Master can easily get serious at a moments notice when his comrades or whatever he is protecting is in danger.
During his younger years, he acted as a teacher for the Ace Commander and Ace Gunner while together with the Ace Hunters. He use to be a Hammer user during those years. After a Rathian hunt turned into a Kushala Daora's attack, the Master retired from being injured in battle and left the Ace Commander as the new leader of the Ace Hunters. The Master became an expert in defense against potential monster threats in many cities and towns, such as Dundorma, once he retired. From many people having great respect for him, they just refer to him as the Master. When called to help rebuild Dundorma, he created a new weapon in the Battlequarters called the Demolisher before going to a faraway land. When he left, he gave the Ace Commander his old carving knife.
The Master wears a pale brown robe with an umbrella made of a Rathalos's membrane.