“I never thought I could dream in detail,” Nct’s Mark Lee begins his newly released song, “Toronto’s Window,” expertly kicking off his debut solo album, The Firstfruit.

The 25-year-old K-pop star, known simply by his stage name Mark, debuted nine years ago as a member of Sm Entertainment’s mega-group Nct and is still learning new things about himself creatively. “I really got to find myself while creating this album,” Mark tells The Hollywood Reporter on a Zoom from Seoul, South Korea. “Now that it’s done, it even put me on the idea of my second chapter.”

As one of the busiest working performers in the world of K-pop — Mark is a member of Nct subgroups 127 and Dream and has worked in supergroup SuperM, along with other Nct formations — the Canada-born singer and rapper has never shied away from a challenge. On The Firstfruit, Mark gets vulnerable...