Whenever Ayaka goes outside, she wears a mask. The mask, she explains, prevents her from inhaling radioactive dust. She is allowed to play outside only at weekends, and then only once her father has checked for radiation. Grass and plants draw radiation, so Ayaka is allowed 30 minutes of play in the middle of a car park. Then she must return inside.
Ayaka is one of the children featured in Japan: Children of the Tsunami on BBC2. Her family home was destroyed in the tsunami that hit Japan in March last year. Her grandfather was killed and her family forced to evacuate the area after shockwaves sent the nearby nuclear reactor into meltdown. "Now all we have left is the pain," the 10-year-old says.
Japan's children are likely to be most affected by the fallout, both nuclear and psychological, from the disaster. And so this one-off documentary offers a child's-eye view of ongoing events.
It was almost the end of the school day when the tsunami hit. At Okawa primary, 10-year-old Fuka was celebrating her friend's birthday. "We surprised her and wished her happy birthday," she says. "Manno was my best friend. She was really lovely - always happy and smiling." In the banality of her description, the past tense is striking.
Ten teachers and 74 children died at Okawa primary. There were 17 children in 10-year-old Soma's class; only four survived. "They're probably watching from above," he says. "I think they're studying with me at school. They're my friends and I don't want them to leave me. I don't want everyone to disappear."
After the Fukushima nuclear reactor exploded, families were evacuated from high-risk areas. "We had to take a shower and then they threw away our clothes," says seven-year-old Mutsumi. "I loved those clothes, so that made me sad."
Nearby, four-year-old Toshiyuki rides his bike in silence. He has not spoken properly since the evacuation.
But while the psychological effects of the disaster may be immediately apparent, there are likely to be long-term physical effects, too. "If you're exposed to radiation, you'll get cancer and it will hurt a lot," says 10-year-old Rikku. "And you'll die."
"Will I be able to have babies?" Mutsumi asks her mother.
Meanwhile, Ayaka is coming to terms with the fact that it may be 20 years before she is allowed back into the area that was once her home. "I feel locked up in the house," she says.
Ten-year-old Saki used to feel the same way. Now she gazes out of her bedroom window at the exclusion zone. "I've got used to it now," she says. "I've got used to the radiation, so it's OK."
Japan: Children of the Tsunami is available to watch on BBC iPlayer.