Mizuho Bank, one of Japans largest lenders, has became ensnared in North American legal fallout from Mt. Gox, once the worlds biggest bitcoin exchange, which collapsed last month after losing nearly half a billion dollars worth of customers digital currency. Lawsuits in the United States and Canada represent a new legal front – and a deep-pocketed defendant – in the battle over Mt. Gox, which claims hackers stole huge amounts of its own and its customers assets. Mizuho, the core unit of Mizuho Financial Group Inc, Japans second-biggest megabank by assets, was added as a defendant on Friday to an existing U.S. lawsuit against Mt. Gox for allegedly aiding in a fraud by providing banking services to the exchange. Also on Friday, Mizuho was named in a class-action lawsuit in Canada against Mt. Gox, alleging a lengthy security breach at Mt. Gox resulted in the pilfering of millions of dollars worth of its users bitcoins.