Board Thread:Questions and Answers/@comment-67.8.125.220-20170224030817/@comment-217.10.52.10-20170224131449

There is a wikia page that describes the purchase process for various services, but Visa Gift Cards are not among them:

http://kancolle.wikia.com/wiki/Shop/Purchasing

I personally use PayPal - just yesterday stocked up 20 port slots for ~17€.