It's part of the office suite.
One of the installed modules creates that virtual drive. It is nothing to be worried about.
It's due to whichever one uses Click-to-Run
How does Click-to-Run work?
Products delivered via Click-to-Run execute in a virtual application environment on the local Operating System.
This means that they have private copies of their files and settings, and that any changes they make are captured in the virtual environment. The effect is they don’t end up modifying any other software installed on the System.
With few exceptions, only user data actually passes through the virtual environment to the local System. Click-to-Run users may notice that they have a virtual Q: drive on their PCs, this is the virtual file system used by Office.