Kim Ha-na no longer sleeps or eats and is haunted by the voice of her 17-year-old brother, calling frantically to tell her the ferry he was aboard with more than 300 classmates and staff from his high school on the outskirts of Seoul was sinking.
More than 50 people are now known to have died and 252, mostly children, are presumed dead in the upturned hull of the stricken vessel that capsized off the southwestern tip of the Korean peninsula on Wednesday.
Since then, Kim and hundreds of other relatives have spent 24 hours a day waiting helplessly for news in makeshift accommodation at a gymnasium in the port city of Jindo, the centre of the rescue operation.
They live and grieve together, packed into the floor space on narrow, thin mattresses, taking to a communal microphone to vent their hopes and their anger at government officials over the seemingly slow pace of the rescue and patchy information.
Kim's brother, Dong-hyup, was one of 339 pupils and teachers from Danwon High School on an annual outing to the subtropical island of Jeju, making up most of the 476 passengers and crew.
"He called me at 8am, saying the ship is sinking. Then I lost him," said Kim, 22 and a student.
The Sewol ferry took more than two hours to sink in calm waters on a well-travelled 400-kilometre route from the mainland South Korean port of Incheon to Jeju, a journey of 13.5 hours.The gym has become a focal point for anger and fading hope.
It was also the scene of one more tragic death. Kang Min-gyu, 52, the vice-principal of Danwon High School, went missing on Thursday and was later found hanged with his belt from a pine tree outside the gymnasium building.
Kang left a heart-rending, two-page suicide note that was partly released by police, in which he said he could not live while the fate of 200 others was unknown.
"Burn my body and scatter my ashes at the site of the sunken ferry," he wrote. "Perhaps I can become a teacher for the missing students in my next life."
Professional care is available on site; there is free internet and medicine as well as shampoo and soap. But South Korean officials have struggled to cope with the overwhelming tragedy.
Officials took DNA swabs from relatives on Saturday, adding to the foreboding that what had been billed as a rescue mission has become an operation to recover and identify bodies.
"It is a group trauma, not just for parents here but for people across the country. It's not going to be over in one or two months. It is leaving a big scar," said a member of a team of counsellors at the gym, surnamed Yoon, 48.
There's no escape from the tragedy. Endless TV news and footage from the rescue is played on four huge television screens that relay information to the hundreds grieving inside the gym.
When relatives obtained underwater footage of the rescue in the murky waters around the Sewol after divers said they had seen bodies, those watching jeered coastguard officials.
Some heckled President Park Geun-hye when she visited the site on Thursday, a rare occurrence in a hierarchical country where respect for authority still counts for a lot.
The microphone set up on a stage is now used more to give voice to frustration and anger than for expressing any hope, and channels the rising emotions of those waiting largely in fear.
"It will be a miracle if they are alive. I just want to hug my child's body," a father said from the stage to applause from other waiting relatives.