SEOUL (WASHINGTON POST) - SHINee singer Kim Jong Hyun's sudden death has stunned fans around the globe and shed light on his struggles with mental health.

As news spread, fans first responded with scepticism and disbelief. Though the boyband had enjoyed immense popularity in South Korea and elsewhere, they had just earlier this year made their first-ever tour stops in the United States, playing full-length concerts in Dallas and Los Angeles in March.

After SM Entertainment released its statement on Monday confirming the death of the singer who is more popularly known as Jonghyun, tributes poured from devastated fans and fellow artists.

Even in the US, Jonghyun, 27, and SHINee were trending on Twitter, and remembrances often intersected with another trending hashtag, #MyMentalHealthIn5Words.

Fans also pointed to his final Instagram post, made on Nov 20, that included a screenshot of song lyrics from Beside You, a song by another K-pop group named Dear Cloud: "Crouched my body in a dark room and thought to myself / Will you one day regret letting go of everything / Will the constant wounds and exhausted sighs come to a stop / I pray you are no longer in pain / All I wish is for you to be happy / Please don't stay in darkness alone / Don't torture yourself / Don't torture yourself / Please."

He was found unconscious on Monday at a hotel in Seoul and rushed to hospital. Police have not yet ruled the death a suicide and an autopsy will be conducted, local news outlets reported.

The five-member SHINee broke into the Korean music scene in 2008, and Jonghyun shot to fame for his varied, emotive vocals and stage presence.

He also developed a successful solo career, frequently collaborating with other artists and making appearances on shows like Saturday Night Live Korea.

"SHINee are a really innovative boyband, and they really represent how K-pop is this very innovative, boundary-less music scene," K-pop expert Jeff Benjamin said.

"Jonghyun debuted as a teenager, and I think a lot of people felt like they grew up with him."

Mr Benjamin, an editor at Fuse TV who has also been a K-pop columnist for Billboard for five years, said he came to appreciate Jonghyun's thoughtful approach to music-making, as well as his signature way of singing.

However, he hesitated to compare SHINee to an American boyband because, unlike a lot of US groups, SHINee have maintained relevancy and strong record sales for nearly a decade.

"Our boybands tend to maybe not age so gracefully," Mr Benjamin said. "(SHINee are) still just as hot as they were."

Also rare was the group's cohesion. Since SHINee's inception, no one has left the band and there was never any public drama. Mr Benjamin said he asked Jonghyun about that when they last spoke earlier this year at KCON in Los Angeles.

"He actually specifically talked about the importance of giving each other physical and emotional space," Mr Benjamin said.

"Despite the circumstances of how he may have passed, which we still need to wait for the autopsy report, it sounds like he was very much thinking about mental health and how to best navigate that or survive."