Saito Mari, a 28-year-old nurse, was frustrated. Her pay, at just ¥160,000 ($1,100) a month, was meagre; after bills, rent, shopping and a few holidays, she had little left over. So in 2020 she decided to buy some stocks. “I used to think it was too risky,” says Ms Saito, who learned about investing via books and YouTube. “But it was amazing to see my assets grow.”