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.
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.
Prime Minister Shinzo Abe says he is keen to expand programmes for foreign workers including nurses but says they would be required to go home after three to five years.
"What the government is doing is not going to address the serious population collapse that Japan faces," says Hidenori Sakanaka, executive director at Japan Immigration Policy Institute.
"Japan needs 10 million immigrants over the next 50 years and we need to accept them as new members of our society," he says.
"If we educate our young people that Japan needs to become more multiracial to tackle the population problem, I think we can achieve it without causing major problems."
But his opinions seem optimistic in light of a recent column by well-known author Ayako Sono.
While Ms Sono supported removing strict requirements to allow more foreign workers to enter Japan to look after the old, she said these workers should live in separate communities - prompting claims she was advocating policies similar to apartheid.
Her views are not mainstream. But the service industry, which hires foreign students as part-time employees, also received harsh feedback, especially at the beginning, from those unused to dealing with foreigners.
"In our survey, customers asked why they had to be served by waiters who cannot speak Japanese properly," said Naoki Ishino of restaurant chain Negishi. "Some simply asked why we were hiring Chinese people.
"There were also cultural differences. For example, our foreign staff found it very difficult to apologise when a customer complained about a mistake made by a colleague."
After training them under a supervisor from their own country, Mr Ishino says things started to improve.
But allowing a limited number of foreign students to work in restaurants is a far cry from the influx needed to care for Japan's rising number of elderly people.
And there are no immediate solutions on the horizon.
"Japan has been excessively conservative about the introduction of immigrants and we need to deregulate," says Seijiro Takeshita of Mizuho International.
But he says Japan needs to be sure this would not harm "the homogeneous group ideology", given that "failure of multiculturalism in Europe" has, he says, led to social conflict.
Midori says she enjoys caring for her grandmother but she's likely in a minority.
She also has elderly parents who will soon need to be looked after. For those who don't have a relative to help them, with indigenous resources overstretched, the future is a worry.
Japan needs to find a solution, fast.