Martunis owns a small, old-fashioned suitcase and carries it as if it's the most precious thing on Earth.
He puts it on the floor in front of him, kneels down and flicks open its anachronous brass locks.
Bigger than a lunchbox and smaller than a briefcase, the case holds a thin, half-empty photo album and a pile of neatly folded soccer shirts.
The first shirt is only big enough for a child. It is weathered and torn and the bold red colour of the Portuguese soccer team has been faded by the sun into a dull pastel.
"I wore this for the 21 days I was floating in the sea," Martunis smiles, calmly recalling one of the 2004 tsunami's most amazing survival stories.
"I am very happy when I hold this. To me this brings good memories and I am proud of this shirt."
Miracle boy: Banda Aceh tsunami survivor Martunis.
Martunis was eight when he was found alive and wearing that shirt - dazed, disoriented and close to death - three weeks after the tsunami had flattened his home city of Banda Aceh.
His 21 days adrift stunned doctors and aid workers, who had all but given up hope of finding any more survivors, let alone a small boy.
He became a symbol of hope in a region that desperately needed some.
Almost 10 years later, The West Australian has found Martunis, now 18, in Banda Aceh, still carrying the Portuguese shirt, the oldest thing he owns.
He says he vividly remembers December 26, 2004.
He was in a car with his mother and sister trying to escape the rising water when they were engulfed. Martunis lost sight of them as they were pulled under water but he managed to cling to a school chair, then a mattress, then a tree and then a sofa.
He was swept across the city and out to sea and for the next three weeks he was surrounded by bodies and survived on packs of noodles and water bottles fished out of the ocean.
He was alone in the water, night after night, surrounded by debris and bodies - an eight-year-old who thought he was the last living person on Earth.
"I was at sea for 21 days and saw no one," he remembers.
He was eventually found on a beach, dehydrated, disoriented and covered in mosquito bites. He was handed over to a Save the Children team working in Aceh.
Mohammad Hatta, who worked for the organisation and could speak Acehnese, was tasked with looking after him.
"I brought Martunis into the hospital and I said, 'this kid has just been found today'," Mr Hatta says, sitting by an inlet on the outskirts of Banda Aceh.
"I think at that day, he was on his last bit of strength. If he hadn't been found then, he would no longer be with us."
He took Martunis to hospital where the boy was recognised by another survivor, who told Mr Hatta that though Martunis' mother and sister had died, his father was still alive.
"I said to his father, 'He is still confused and trying to process everything. Take it slowly'," Mr Hatta recalls.
When his father walked to the hospital room, Martunis just stared and didn't say a word. "I said, 'Do you know him. This is your father'," Mr Hatta said. "Then his father walked over and Martunis started crying."
It is late afternoon in Aceh - almost a decade after that reunion - and Martunis wants to go to the beach near his home.
He kicks a soccer ball across the sand, says he wants to become a professional football player, and tells the story about the other three shirts he keeps in his small suitcase.
One, signed by the entire Portuguese national soccer team, was given to him when his survival story made headlines around the world: the boy who lived at sea for 21 days while wearing a Portuguese soccer shirt.
Martunis' survival story became a symbol of hope after the tsunami and he was "adopted" by soccer star Cristiano Ronaldo. Picture: Steve Pennells/The West Australian
That news was all over Portuguese TV and the national team flew him and his father over to visit and raised money to help them rebuild their home in Banda Aceh.
The third shirt, in the team's white away design, is signed by superstar Cristiano Ronaldo, who met Martunis and called him his "adopted son".
The half-empty photo album that he keeps in his suitcase has photos of the pair. For a long time, Martunis had Ronaldo's mobile number but lost it when his mobile phone was stolen.
"If he reads your story," Martunis says, "maybe he will call me."
Martunis and soccer star Ronaldo.
The fourth team shirt, also given to him by Ronaldo, is the one of which he is most proud, the one that bears his name, Martunis, and the player number: one.
"He's a tough kid," Mr Hatta says. "He found a way of coping. And he survived. No one expected it."