this is super junior KRY
ahem, if yu dont know what they are it basically Kyuhyun, Ryeowook and Yehsung. They use the first letter of the name thus making it KRY !!
lol, this is them doing the acapella of Endless Moment, they are called the most talented voices of the group.
yehsung looks so cute, when he forgets the words. his smile makes you weak in the knees ^^,