Los Campesinos!, a pop septet from Cardiff, Wales, were an inspired choice to open the Marine Stadium stage at Summer Sonic Tokyo last month. Each tune kicks off with a catchy riff and proceeds to burn rocket fuel as lead vocalist Gareth twitches and yelps — nothing the band plays is slow, or even mid-tempo. Not yet blasted by alcohol and sunshine, the audience literally danced to beat the band. There was nothing for Gareth to do but plunge straight into the teeming mass — a good 2 meters below.

"It was quite a drop," he says later in the press hospitality area, where he's taking questions with bandmates Ellen and Neil. "I do it sometimes, but only if things seem to be going well. Fortunately, I remembered to bend my knees."

On stage, Gareth is the most visibly arresting member of the group, but he doesn't come across as the leader or even the main person. In line with their name ("the peasants" in Spanish) and the fact that they replaced all their surnames with Campesinos for professional purposes, the band is a true collective of equals. When heard for the first time, their music brings to mind hyperactive preadolescents locked in a roomful of musical instruments. They channel this quality into sophisticated songs, a testament not only to their creative focus but also to their camaraderie.