However if this is an Android with the usual there are WiFi HDDs with apps to do this.
Examples at http://www.newegg.com/Product/ProductList.aspx?Description=wifi%20hard%20drive&Submit=ENE
I understand I can buy an OTG adapter but how do I get the app to run it?

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic