On October 16th, 2PM's Junsu announced via his Twitter that he will be changing his name.

He tweeted the following tweets,

BECAUSE OF A FAMILY MATTER, IT WAS DECIDED TO CHANGE MY NAME.

� Jun. K (@Jun2daKAY) October 16, 2012

OFFICIAL STAGE NAME WILL BE "JUN. K" AS IT WAS BEFORE BUT THE REAL NAME HAS CHANGED TO "MIN-JUN". JUNSU WILL NO LONGER BE USED IN THE FUTURE � Jun. K (@Jun2daKAY) October 16, 2012

He also wrote the same message in Japanese and in Korean. He didn't explain the sudden change of name except that it was because of 'a family matter'. The singer explained that he would be keeping his solo name of JUN.K, but did not elaborate if his name in 2PM would change from 'Junsu' to 'Minjun'.

Why do you think he went through the sudden change in name?

Source: JUN.K's Twitter