These exchanges seem like a real achilles heel in the crypto space.
We had the NEM (XEM) fiasco last month where more than $500 million of the cryptocurrency were stolen from a Japanese exchange called Coincheck and a glitch with Coinbase more recently where peoples bank accounts were drained and the list goes on.
There seems to be yet another supposed glitch where an exchange called Zaif which of 1 of the 16 officially recognised exchanges in Japan allowed 7 people from Japan to purchase a mammoth amount ($20 trillion) Bitcoin for $0.
Zaif has since voided 6 of those 7 transactions but it seems they are having trouble with one of them, these kinds of transactions are not actually possible as the current market cap of BTC is $181.5 billion and the amounts mentioned far exceed the total BTC in existence.
There is not a boatload of information on these events but you can read more about it HERE.