HUDDLED over the viewfinder of The Straits Times photographer's camera, North Korean sisters Kim Hye Song and Kim Hye Gyong giggled excitedly as they pointed at images of themselves.
This brief moment of girlish spontaneity belied their default sombre facade, and allowed a fleeting glimpse into their identities as national athletes from a country shrouded in much secrecy.
Soon, the 20-year-old twins - touted as the future of women's marathon running in North Korea - were whisked away with all interview requests rejected, ahead of the Great Eastern Women's Run.
Their entry onto the world stage, however, was not that muted.
Coming from relative obscurity, the younger Hye Gyong stormed to an eighth-place finish in the marathon at August's World Championships - in only her second overseas competition.
Running under hot and humid conditions in Moscow with temperatures rising to 34 deg C, she clocked 2hr 35min 49sec to mark North Korea's only top-10 finish in the women's marathon at the championships since 1999.
Hye Song also competed that day, finishing 14th in 2:38.28.
Jong Myong Chol, their coach of seven years, believes that the sisters enjoy a healthy rivalry which has spurred their development over the years.
Speaking through a translator, he said: "Although they are sisters, they are also competitors to each other so they challenge each other and they push each other during their races.
"I train them to challenge each other but only during the race.
"Once it ends, they are friends and sisters. There might be a difference in their (race) positions but there are no problems at all."