Due to recent server problems Nintendo is facing with their eShop, they were forced to remove the Pokemon Bank that was recently published on the Japanese server.
Nintendo has not confirmed when the service would be returning to Japanese consumers, but they did confirm that those who had started their 30 day free trial would have their time restart once the service was reinstated.
The main concern that fans outside of Japan had was if the Western release of both Pokemon Bank and the Poke Transporter would be delayed. Nintendo actually confirmed this would be the case, sadly, as we were supposed to gain access to the service today.
In the interim, Nintendo has taken their eShop offline across both the Wii U and the 3DS, and has issued apologies and has asked their fans to be patient while they fix the problem.