Custom domain name of SharePoint 2013 app

Let's say our SharePoint 2013 online url is http://ift.tt/1wO5r22

Is it possible to add a subsite (like an application under IIS website) that launches a SharePoint app?

I created a sample SharePoint 2013 app in Visual Studio and deployed it to SharePoint online, and got a long isolated url like http://ift.tt/1tLLYUA

I'm wondering if the app can be accessed under the same root domain as shown in the picture below, something like http://ift.tt/1wO5r24.

If this is not possible, how are users supposed to access the app? Like the developer provides the isolated domain link to the app in a page?