Close to 40 employees from law firm Morrison and Foerster attended the game in Toyota on Saturday night decked out in Manu colours, after being 'recruited' by colleague Louise Stoupe, a proud New Zealand born Samoan.
Stoupe is a partner in the American firm's Tokyo office and admits she was the driving force behind the firm's decision to sponsor the Samoan team earlier this year.
"Morrison and Foerster supports talent basically and that's one of the things we were keen on supporting - Samoa's got a lot of rugby talent with not a lot of financial support so we wanted to bridge that gap," Louise Stoupe said.
Stoupe has lived in Japan for 18 years and said it has been fantastic to watch the country fully embrace the World Cup.
"It's fabulous because the vibe of rugby here has just been increasing and everyone is getting very excited again and it's great to have Samoa in the same pool as Japan," she said.
A massive rugby fan, Stoupe was in the stands to watch the Manu beat Russia in their opening match of the tournament in Kumagaya.
She then convinced around three dozen of her largely Japanese colleagues to attend the game against Japan in Toyota but with a catch - they had to support Samoa.
"They've been very keen," she insisted. "As you've probably seen Japan has really embraced the Rugby World Cup and they are keen on supporting the other teams and making sure everyone has a good time here."
But how did she convince them to attend the game decked out in Samoan blue?
"It took a little bit of convincing," she admitted, "but we got them there."
"They came in the red and white and I had them put the blue on top so let's see how it goes."
The bloc of blue was even given a list of chants and songs to belt out during the match, while they also impressed with their rendition of the national anthem.
The group clearly followed instructions and while Samoa was beaten 38-19 by the host nation, the group made an impression on Manu Samoa head coach Steve Jackson, who managed to pick them out from a sea of red and white.
"I think we had about 500 Samoans in the crowd tonight - there was a little square of blue as I sitting across the grandstand," he said during the post-match press conference.
"It was just all our families, I think, and at times we could hear them so just a great atmosphere."
Despite living in Japan for nearly two decades, Stoupe said there was never any doubt over her allegiance at the weekend.
But with Samoa's quarter final hopes now over she and the rest of the firm are now free to give the Brave Blossoms - including two Samoan players - their full support.