No one did it for Japan first probably because they have pretty strong criminal liability stuff for securities violations and other financial crimes and don't play the "no fault settlement" game.
It's not illegal to arbitrage but yeah I think what you are pointing at is you have to be regulatory-ily buttoned up for Japan markets vs a more loose market where you don't have to be super careful & can learn as you go.
So SBF having been in finance before (Jane Street), he knew where the footsteps were and how to do it vs a fly-by night crypto investor with no finance background.
Supposedly the Japan “subsidiary” (if you can call it that) was set up by a Japanese person and a resident of Japan, who was a contact of SBF through the Effective Altruism thing. I think they knew something was shady, because the account they had opened in Japan was with a small rural Japanese bank.
When that “arbitrage” turned out to be really lucrative one of the founders of Skype (Talinn something) gave SBF a $50 million loan. SBF and that Talinn guy knew each other also from that Effective Altruism sect-like thing.
All this info was part of a Sequoia congratulatory piece on SBF, they of course had also given him money. The article has since been taken down, it’s still reachable through Web Archive.
