Mobile content production company MOMO X featured Sunmi for their 'Big Gains 2' segment. For the show, Sunmi confronted a seller who attempted to sell the Wonder Girls' 'Why So Lonely' album on a used auction site for 10,000 KRW (around $9) each. 

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A staff member went out first to buy the album from the seller while Sunmi watched the scene live from the side. 

Then the idol confronted the seller herself and exposed her identity. The seller reacted very surprisedly. It turned out the seller is actually a long time loyal fan of Sunmi. The idol star also recognized the fan from past fan sign events. 

The fan explained that he has purchased 30 copies of the Wonder Girls album and had to sell several in order to save up for traveling. 

Sunmi jokingly scolded the fan for selling the albums and made him promote her new album 'Gashina' on the streets. The two then exchanged a sweet fan-star moment with photos and hugs. 

In the interview, Sunmi stated she had much fun and showed understanding for the reason of the sale. She also thanked the fan for being by her side through the past 10 years. 

Watch the full segment in the clip above.