Information:
The name of the group forms the members initials, if you look at them in the order that they're listed on this page. KAT-TUN actually existed a good amount of years before they debuted. They were gathered up from Johnnys Jrs. by Doumoto Kouichi (from the KinKi Kids) to be backup dancers for him, back when he hosted the NHK music program Pop Jam. They ended up blossoming into a full fledged Johnnys group.