Arashi is more pop-infused nowadays. only their earlier works resemble KAT-TUN a bit. they're definitely have an edge to their work. of course they still have idol-pop in their discography, but rock is their main genre. they also have dance-infused songs too. and their image is far more "darker" than Arashi too. the rapper looks like a rapper.
you should probably YouTube "Keep the faith", "LIPS", and/or "DON'T U EVER STOP" to get a feel.
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Michael
Jinckson appeared at the concert:
http://stanime.livejournal.com/132151.html 