It's X4 & Yuya Matsushita. Never heard of either, but am sure they'll be great.
X4 is actually Yuya's group. I don't think he'll be performing his own solo music, but hey, he might. The main reason they mention Yuya specifically is because he was one of our musical guests when FLOW came back for a second time in 2011.For anyone who isn't sure if they want to go to MusicFest this year:
When I went to the 2011 concert, I was specifically going for FLOW and didn't give Yuya a second glance. My friends and I had written him off as a filler act before FLOW. Boy, were we wrong. By the end of his performance, we were all cheering loudly and were enthralled with his performance. You could tell he gave 110% to his act. That night, I definitely became a fan. I think I still hold 2011 as the best MusicFest I've been to and he is part of the reason. So for those who haven't yet seen him (and his group), give them a chance. You might be very surprised.