Worldwide, the gangly teenager sitting cross-legged on the floor of his Aceh living room is perhaps the best known Indonesian survivor of the 2004 tsunami.
On the faded green walls above Martunis are reminders of the happiest, proudest and most confusing moments of his young life.
There's Martunis being interviewed on national TV.
There he is arm-in-arm with FIFA president Sepp Blatter.
And there he's beaming with his idol, Cristiano Ronaldo.
But it's hard to get a smile out of him today.
When the Boxing Day tsunami struck Aceh, the water reached the then-seven-year-old as he was walking to the village soccer field, and eventually marooned him alone in a mangrove swamp.
He survived for 20 days on puddle water and dried noodles before a British TV crew found him and he was reunited with his father.
His mother and siblings were killed.
The boy's remarkable story and the Portugal football jumper he wore throughout it caught the eye of the European media, who thrust him into the spotlight.
In 2005, Ronaldo visited Martunis in Aceh, bringing money for his education, and Martunis visited Portugal.
It was a much-needed good news story at a time of incomprehensible loss.
Ten years on, with his schooling complete, Martunis hangs out with his neighbourhood friends when he's not attending English courses or the Real Madrid Foundation's Aceh soccer school.
The 17-year-old with his hero's haircut sits on the rug and shrugs.
Martunis says his dream is - has always been - of becoming a professional soccer player, "in Lisbon," of course.
One senses his single-word answers are more than teenager behaviour, but also for survival.
Not only was the tsunami traumatic for Martunis, but even the highs that followed were bittersweet.
Ronaldo had years ago given him a mobile phone with his number in it, but it was stolen.
The last time he met "CR7," as he calls the football star, was for a mangrove conservation project in Bali.
"I miss him," Martunis says.
"I wanted to stay in Portugal."
But when the discussion returns to football, and the afternoon's match with a neighbouring team, Martunis perks up.
Although he runs every day and trains at the academy three days a week, his coach says he needs to improve his fitness.
What's not lacking is his spirit and his vision.
He goes to the pile of boots in the corner of the room, and says for today his plan is: "keep practising, keep working hard".
