Idk about Japan, but that might be more common than you might think. Hard cash is hard to track, thus it is main method to keep dirty money. Especially if you aren't obligated to make bank transfer for expensive purchase. I have seen in Asia people bringing huge bag of cash and even gold to buy houses and cars.
I also don't know about Japan, so I could be completely wrong, but it seems insane to me -
1. Money that you keep in cash loses value every second; Japan has a middling inflation rate (1.7% compared to US 3.5% or Sweden 0.7%) but you also lose the value you would get from even the safest investment
2. Money that you keep in cash is typically uninsured; if somebody steals it it is gone, unlike your bank account, plus cash sits around as evidence that you're up to something shady - if the money is in some weird offshore account you can spend decades arguing with the tax authorities whether it's been properly accounted for, but if it's in your sofa you look like a crook immediately
3. He wouldn't have gotten the money in cash to start with; since he got rich through shell companies and straw man accounts, it would've been a risk for him each time he pulled the money out of those accounts and turned out into cash and gold (though to be fair we don't know how he did that - but I don't think he has access to proper yakuza-level money laundering networks), so it would be weird to not try to keep most of it virtual
I could buy it if this was his emergency fund, in case he had to leave the country (and then the gold makes sense), though I maintain that the sofa would be incredibly uncomfortable, but not that this was where he kept
all his illegal money - the author just wants a childish Scooby Doo resolution as usual (I mean how did they even convince a judge to give them a warrant based on the hearsay tip-off from some random billionaire?)
