Both sides had been unbeaten on the road to the final, but up against a team who won the last two Youth Olympic titles, the Japanese went in as underdogs.
In defying the odds they also made history by becoming the first Asian team to win gold in an Olympic ice hockey competition.
“I’m so proud and so pleased that this is the outcome of our teamwork,” said Noro Rio, who was assisted by twin sister Riri in scoring her team’s second goal. “My team really wanted to win gold today.”
Japan turned the game around in the second period as they posted eight shots on goal while Sweden had none. The line combination of Kamada Minami, Shimomukai Hina, and Ito Makoto formed a particularly potent attacking trio.
“Sweden did better in the first period, but after that we tried to fight back,” said Shimomukai, who scored two goals and assisted one. “At the beginning our team was very nervous, but we communicated more with each other.”
By the time Shimomukai added an empty net goal with less than two minutes to go, her teammates – and a packed arena backing the Japanese – celebrated the imminent triumph.
Defeat for the Swedish stung. Many left the ice sobbing, the shimmer of a silver medal around their necks providing little consolation.
“We had a great start, but lost it in the second and third period,” said Linnea Adelbertsson (SWE). “We didn’t fight enough. I don’t have any feelings left.”
Sweden captain Nicole Hall, who scored her side’s only goal in the last minute of the first period, said: “The Japanese are very fast and strong, and better than us today. It doesn’t feel good.”
In the women’s bronze medal match, Slovakia fought back from 1-0 down to beat Switzerland 2-1.
The hosts had taken the lead through Nina Harju (SUI) in the second period, before Slovakia responded with two goals scored within two minutes through Nina Hudakova (SVK) and Nikola Janekova (SVK).
Alessia Baechler (SUI), who was in the penalty box when Janekova scored the winning goal in the second period, was crestfallen.
“We had a lot of chances to score but we didn’t take our chances,” she said. “It was very close. I’m very proud of everybody and it’s so sad that we didn’t win bronze.”
Janekova said she was proud of her team after a tough game. “It was very hard for us to play this,” she said. “It was definitely worrying [that Switzerland scored first]. I have goosebumps.”
In the men's tournament, the USA booked a place in the final after beating rivals Canada 2-1 in the semifinals.
Frank Nazar (USA) and Isaac Howard (USA) scored in the second period.
Canada surged back following Nate Danielson's (CAN) goal early in the third period, but the USA kept them at bay.
The defending champions will meet Russia in the final on Wednesday, after they beat Finland 10-1 in their semi-final.