The Oct 14 death of South Korean singer Sulli, which has been linked to depression, also put the spotlight on Mina.

The singer in popular girl group Twice recently took a break from promotional activities after her agency said the 22-year-old is suffering from anxiety attacks.

However, on Sunday (Oct 20), fans were overjoyed when Mina popped up on stage at the group's fourth-anniversary fan meet at Korea University in Seongbuk-gu.

Posting a photo that showed her wearing angel wings, she wrote: "Our 4th anniversary, thank you."

Mina has lately kept a low profile though she recorded songs and appeared in a music video for Twice's eighth mini-album Feel Special.

The singer, who is Japanese, reportedly was harassed by netizens after relations between South Korea and Japan became frosty over economic issues.

There is no word if Mina will take part in Twice's upcoming world tour, which kicks off in Japan on Oct 23.

Her agency is playing it safe, saying: "We will prioritise the state of her health above all else when coming to a decision."