Conversation so far:
What is the club name where the band Flotsam and Jetsam played in Japan ?
The band Flotsam and Jetsam played at Citta Club in Tokyo
What is the name of the band who performed at the Citta Club in Tokyo Japan?
The name of the band that performed at the Citta Club in Tokyo, Japan is Flotsam and Jetsam
Where was the band Flotsam and Jetsam formed?
The band Flotsam and Jetsam formed in Phoenix, Arizona
What was the name of the concert the band Flotsam and Jetsam performed between 2013 - 2014 ?
In June 2013, the band Flotsam and Jetsam headlined at the Warriors of Metal Festival in Columbus Ohio

Question: Who was the lead vocalist at the concert ?
Self-contained rewrite: Who was the lead vocalist at the band Flotsam and Jetsam concert?