https://qooah.com/2015/05/16/softbank-%e6%96%b0%e5%bb%a3%e5%91%8a%ef%bc%8c%e4%b8%80%e5%88%80%e6%96%ac%e6%96%b7-docomo-%e7%82%b8%e8%9d%a6%ef%bc%81/