There are many different HTC Nexus 9 cases of different kinds and it won't be a problem finding many choices for the item that you want, the true issue for you will be selecting the item that can provide you with the qualities that you truly need.
The satisfaction you will experience from that case that you are going to get is a direct result from the goals and qualities that you are going to input into your quest for the case that suits you the most. There are many different cases out there and you need the know what to look for before you start looking.
One of my favorite cases for the HTC Nexus 9 are keyboard cases. I like to travel and I always take my tablet with me when I do so. When I travel I always keep on writing and working from different hotels across the world and it is much easier writing when you have a keyboard.