K-pop girl group Red Velvet IRENE's secret behind her legs is finally revealed! 

At an online community, a picture of IRENE wearing foot massage slippers was uploaded. 
In the picture, IRENE was wearing foot massage slippers, which had jade gravels on the bottom of the slippers. 

She also made an appearance in JTBC 'Knowing Bros' and shared her experiences with foot massage slippers. 
She said, "After I started to wear foot massage slippers, my legs don't get swollen." She also added that now rest of Red Velvet members and staffs wear foot massage slippers as she recommended.

Meanwhile, Red Velvet released its new track 'Red Flavor' recently, and have swept K-pop music charts. 

(Credit = Online Community, JTBC 'Knowing Bros' Screen Captured)  

(SBS Star)