So how much will we receive?
20% of the bitcoin lost?
Maybe less considering that the price of bitcoins has increased? (so the ones who had money will get more)
If your claim is accepted, then you now know the amount in JPY you will be handed. For bitcoin there was a fixed price for it when this is officially announced (and the pdf was out); IIRC roughly 50500 JPY per bitcoin. So if we want to make the assumption that our claims will be delivered according to this, you will have to divide that amount with bitcoin's current value to come up with the bitcoins you will end up with.