A 10% cut wouldn't be $100. It sounds like each person ran about 140(!) transactions, maxing the withdrawal on each one. That's 14 million yen per person or about 127,000 usd. 10% would be 12,700. Still possible that this happened but my guess is it was yakuza given the coordination and manpower.
As someone upthread remarked, it actually seems improbable it was yakuza - way too visible, even with no provable connection, going to make their lives problematic for awhile.
Plus, we probably wouldn't be hearing about it a week after the fact, if it's part of a long-standing interaction like the yakuza, barring someone with loose lips.
