One of the three so-called Japanese "megabanks" (along with Mitsubishi UFJ Financial Group and Sumitomo Mitsui Financial Group)
To put it into perspective: the Mizuho bank that provides banking services for this unheard of nonentity you call MtGox among many (MANY) others is just about large enough that MtGox accounts for about five minutes of their volume. Every 25 to 128 years.
It is interesting that a comparatively small amount of wire transfers which came from MtGox customers have caused their entire wire systems API to fail.
Like I said earlier I don't believe it for one minute.
The bank have given out a bullshit excuse. I'd really like to know the real reason behind this.
It's possible (or even probable) that the MtGox contact at the bank also knows nothing about the real reason behind this.