Several times a night, Midori Ide wakes up to help her 96-year-old grandmother use the toilet. To make sure she can assist immediately, Midori sleeps right next to her grandmother.
It is not a duty that many 29-year-olds would enjoy. But she tells me she feels guilty that she can only do it once a week.
Midori works the other six nights of the week at a nursing home caring for other elderly people while her grandmother stays at a different facility.
"It's a dilemma but I need to earn money because my family isn't wealthy," she said.
"I also want to continue working because ever since my grandfather died when I was 15, I've decided to become a care worker and it is my calling."
But it comes at a cost. Midori dreams of going abroad. She misses spending time with her friends.
"I don't want my grandma to hear this but I am almost 30 and I worry if I can start my own family one day," she whispers.
"But I don't want to think about when my grandmother will stop waking me up. I want to be with her when she achieves her dream of turning 100," she says.'Too tired'
Midori is one of 177,600 people in Japan aged between 15 and 29 who are caring for a family member. Not many would be as content as her with their decisions.
There is also a growing number of households where one elderly person is looking after another in need of nursing care.
Just last month, a 71-year-old husband was arrested for killing his wife who had dementia. "I got too tired from looking after her," he confessed, according to local media. "I wanted to take my own life, too."
It was not a one-off tragedy. And they are the real people behind some staggering statistics about Japan's ageing and shrinking population.
Today, more than a quarter of Japan's population is aged over 65. This is set to increase to 40% by 2055, when the population will have shrunk from the current 127 million to 90 million.
The Ministry of Health, Labour and Welfare has warned that Japan will need to add one million nurses and care workers by 2025.
Encouraging immigration may seem like a simple solution - but it's not a popular one.
Japan is still one of the most ethnically homogeneous countries in the world, with foreigners making up less than 2% of the population. Opening up Japan to large-scale immigration is a very sensitive subject.
In 2008, the government started allowing foreign nurses and care workers in.
But the bar is set high. Having to pass the national exam in Japanese is incredibly difficult and only 304 foreign nurses and carers have so far managed to make Japan their temporary home.
For further details, http://www.bbc.com/news/world-asia-31901943