Benjamin 'Moonhead' Mercury Vetaas came to jiu-jitsu through judo at the Kodokan Institute in Japan, then pivoted to BJJ under one of the few coaches in the world whose name is synonymous with leg attacks: Masakazu Imanari at Imanari Jiu-Jitsu Tokyo. Imanari himself promoted Vetaas to black belt in January 2025, with subsequent certification through Eddie Bravo and Frode Nilsen of 10th Planet.
Since Season 11 in 2025 he has been the head coach of 10P Bergen, the country's first 10th Planet affiliate, where he runs a curriculum built around rubber guard and the lower-body system that brought him through the ranks. Every competition win on his record so far has come by leg lock — a stat that says more about his identity than any belt rank.
He now splits his time between Norway and Japan, carrying a direct technical line from one of the most distinctive grappling rooms in Tokyo straight into a Bergen mat.