By Friday, the group had amassed a support petition with more than 150,000 names, and organisers say Japan's 128-million residents are now among the possible candidates for the prestigious award.
But even if the odds are slim -- there are hundreds of candidates -- the message is just as important, said 37-year-old housewife Naoko Takasu, who came up with the plan.
It was not possible to nominate Japan's pacifist constitution -- put in place after the end of World War II -- so activists moved to get the peace-loving population on the prize list instead.
"The idea came to me when I was watching a TV report about the Nobel Peace Prize awarded to the European Union," she told AFP.
"Good initiatives can win the prize -- that's what I learned from the news. And that made me think about Article 9 (of the constitution)... If we succeed and win the prize, that would be a great way to share its ideals."
Japan's constitution -- specifically Article 9 -- renounces war and abandons the use of force to settle international disputes, a point embraced by many Japanese and a symbol of the country's peaceful image in much of the world.
But last week, Tokyo loosened the bonds on its powerful military, proclaiming the right to go into battle in defence of allies, in a highly controversial shift.
Conservative Prime Minister Shinzo Abe's cabinet formally endorsed a reinterpretation of the rules that have banned the use of armed force except in very narrowly-defined circumstances.
- 'War destroys everything' -
Abe has sought to play down fears the move could ultimately see Japan dragged into battle to defend allies, or wage war itself.
But it has sparked a backlash at home and drawn angry missives from neighbouring China, which regularly criticises Tokyo's militaristic past.
"It is thanks to Article 9 that Japan has never been in a war for over 69 years," said Yoshiaki Ishigaki, a member of the committee behind the push.
"This decision is totally against our constitution, we should maintain the article and share it with all nations to achieve world peace."
Ishigaki and other activists gathered recommendation letters from dozens of academics at home and abroad to submit to the Nobel committee.
At least half Japan's population opposes a more aggressive military stance, according to recent newspaper polls.
Hundreds, and sometimes thousands, of people have turned out to protest against the change at various demonstrations over recent weeks.
"War destroys everything, that's what I have believed since 1945," said 80-year-old Tsuneo Hoshino, who lost an uncle in World War II.
"I am the head of nursery school -- these children should never be soldiers."
The names of the 2014 Nobel Laureates will be announced in October.
Last year the peace prize went to the Organisation for the Prohibition of Chemical Weapons.