Hopefully everything will be alright!

U-KISS's AJ revealed that he recently underwent heart surgery,surprising many fans.

While the rest of the U-KISS members are in the middle of promoting "Stop Playing," fans were aware that AJ was away from promotions. The rapper spends half of each year studying at Columbia University in New York City, and fans assumed that was where AJ was spending the promotional period.

However, on June 11, AJ posted a picture on Twitter showing his arm hooked up to an IV, wearing a hospital bracelet and a hospital gown. The caption read: "After the heart surgery, I am in recovery."

The tweet came as a shock to fans, who hadn't been aware of AJ's condition. Idols often get sick due to their intense activities, and fans are constantly worrying about idols being overworked.

AJ is the second high profile idol to have surgery this week; SHINee's Onew also underwent surgery due to problems with his vocal chords.

Heart surgery is extremely dangerous, but AJ's tweet implies that everything went well.

Based on the picture, AJ is definitely not in New York, but had the surgery the Seoul National University Hospital.

Prior to the tweet on June 11, AJ's last post had been on May 13. He had expressed excitement about finishing his freshman year at Columbia. That was the last fans had heard from him prior to the worrisome news.

U-KISS's Kevin, Soohyun, and Eli took to Twitter to show their support and worry towards AJ.

Kevin said "I'll be praying for a quick recovery! Don't be in pain" and then made crying emoticons using Korean letters.

Soohyun expressed concern, saying "what why are you like this??"

Eli simply said "Jaeseop [AJ's real name] have strength."

The member's reactions have made fans worry about whether this was an emergency surgery, since Soohyun seems to be asking what was going on with AJ. However, Soohyun may have very well merely been expressing his frustration, asking something along the lines of "why is this happening?"

Nothing is clear at the moment, but hopefully AJ will recover soon, and be able to meet the other U-KISS members and U-KISS's fans when he's restored to full health.