On Tuesday, Jin, the oldest member of the K-pop phenomenon BTS, began 18 months of mandatory military service in South Korea.
Dozens of fans braved freezing, snowy weather to speed him on his way to his boot camp in the eastern county of Yeoncheon, where frontline troops are deployed on guard against North Korea.
BTS announced plans in October to sever their military service, starting with Jin, who turned 30 on December 4, after having postponed his service for the maximum time allowed. The band will reunite in 2025 after pursuing individual projects.
After five weeks' training at the camp, about 45 km (28 miles) from the heavily fortified Demilitarized Zone that separates the two Koreas, Jin will be deployed to a unit that has not yet been specified.
"Now it's time for a curtain call," Jin wrote on BTS fan platform Weverse early on Tuesday before entering the camp in a car.
On Sunday, he shared a photo of his shaved head and joked it was "cuter" than he imagined.
BTS' management, Big Hit Music, said there would be no official event and asked fans to avoid traveling to the boot camp, citing safety concerns.
South Korea requires military service for two years from all able-bodied men between the ages of 18 and 28. It revised the law in 2019 to let globally recognized K-pop stars delay signing up until 30.
Some lawmakers have pushed for a shorter term, granted to medal winners at the Olympics and Asian Games, as well as some classical musicians, but the bill is still pending.
On Tuesday, Yonhap news agency said another BTS member, Suga, has been judged unfit for active duty and would do community service instead.
Big Hit declined to confirm the report on privacy grounds but said all band members would fulfill their duties.
Many artists have received the "entertainment soldier" designation to allow them to keep a hand in by performing for troops or appearing in propaganda.
South Korea's defense minister has said BTS would be able to perform overseas while in the military.