Muirhead's team were not newcomers to this situation, as the same team won bronze four years ago in Sochi by beating Switzerland 6-5, but on this occasion they come up short after costly mistakes in the last two ends including a panicked final shot in an attempt to steal the win from Muirhead.
"When you have a chance to win the game, you're going to have a go at it. I'm gutted I missed the last shot," said Muirhead.
"It just didn't come off and I think that Curling is a game of inches.
"I'm devastated because as a team, we've played solid and we did everything to get that medal but unfortunately it wasn't to be."
Adams added: "We're gutted. It's been a pretty tough week and unfortunately we didn't come out with the medal this time."
After a stalemate at the start of the second half as Japan refused to give up the hammer, Japan's Satsuki Fujisawa pulled her team level with her final stone at 3-3 after a tense eighth end.
Lauren Gray and Vicki Adams looked concerned after a crucial error in the ninth end of the Bronze Medal Final with Japan
Image credit: Eurosport
A nervous ninth end saw Japan overtake Muirhead's team as an error in judgement from Muirhead saw her take out two of her own red stones on an attempt to use a guard to knock out Japan's single yellow stone. But it back-fired completely as the two safe stones spun despairingly out of the house.
Despite a good shot from Sloan in a desperate attempt to force an extra end, the final shot of the match from Muirhead was released in sheer panic and her stone knocked a Japan yellow into the middle of the house to confirm the Japanese team as the 2018 Olympic bronze medallists.
But Sloan says she's hopeful for the future in the next Olympic cycle for the Beijing 2022 Winter Olympics.
"We take pride in everything we do," she said.
"Of course, we were going to go for the win today when the final shot's there but that didn't work out. I think the whole game, we felt good and we felt in control but I'm proud of the team, proud of myself and everyone that has been around us for the last four years and we look forward to the next one.
"Everyone has been behind us and we really appreciate it."