Nojo started her nonprofit "NO YOUTH NO JAPAN” in 2019, while she was in Denmark, where she saw how the country chose Mette Frederiksen, a woman in her early forties, as prime minister.
The time in Denmark, she said, made her realise how much Japanese politics was dominated by older men.
Keiko Ikeda, a professor of education at Hokkaido University, said it was important for young, worldly people to raise their voice in Japan, where decisions tend to be made by a uniform group of like-minded people. But change will come agonisingly slowly, she said.
"If you have a homogeneous group, it’s impossibly difficult to move the compass because the people in it don’t realise it when their decision is off-centre," Ikeda said.
Nojo dismissed a proposal this week by Japan's ruling Liberal Democratic Party to allow more women in meetings, but only as silent observers, as a poorly-executed PR stunt.
"I'm not sure if they have the willingness to fundamentally improve the gender issue," she said, adding that the party needed to have more women in key posts, rather than having them as observers.
In reality, Nojo's win is only a small step in a long fight.
Japan is ranked 121st out of 153 countries on the World Economic Forum's 2020 Global Gender Gap Index - the worst ranking among advanced countries - scoring poorly on women's economic participation and political empowerment.
Activists and many ordinary women say drastic change is needed in the workplace, and in politics.
"In Japan, when there's an issue related to gender equality, not many voices are heard, and even if there are some voices to improve the situation, they run out of steam and nothing changes," Nojo said.
"I don't want our next generation to spend their time over this issue."