MtGox starts an IPO of 500 million dollars
IPO probably doesn't mean what you think it does because no Bitcoin related company has ever had an IPO. The timeline for a public offering is measured in years and requires solid revenue, operating history, and a minimum capitalization. MtGox doesn't meet the criteria for listing on any exchange, and is currently in bankruptcy so that is dead in the water.
In the real world an Initial Public Offering isn't something done trivially. Even coinbase or bitpay have no shot of an IPO today, maybe in a couple more years if they continue to be well run, and grow their businesses.
You may mean a private placement? A debt for equity swap is one method of funding a private placement. There are two issues with that, the first is private placements are limited to accredited investors and in Japan they are limited to 49 shareholders.