IU even playing bartender, mixing her special "Ai-sul" (IU + Chamisul) soju cocktail at the ‪‎하이트진로‬ ‎Hite Jinro‬ ‎Chamisul‬ popup store on April 10, 2015.

I can't read Korean, but I think it says the location is Hongik University, Tokyo Night Market and she will be singing the "Chamisul Song" during the mini concert, too.

I hope she gets drunk, drinking with the fans that night! kekeke

source: link (There are SEVERAL other Korean news agencies reporting on this, also.)