Kazuya, Hi,
As I was reading your post I began to see if your I/O was replicable. Unfortunately, my kali works flawlessly, so I was not able to reproduce your output and some of the input commands do not apply to my architecture. In other news, I found some hope for you: https://www.virtualbox.org/manual/ch04.html here. It is a detailed walkthrough for installing guest additions INSIDE the VirtualBox. Maybe that is why it isn't working the way you'd expect. Always install the guess additions inside the VM, your Host OS is only a proxy, where you download it. Also, check: http://docs.oracle.com/cd/E36500_01/...additions.html here. The second link is more visual. Finally, you could follow this post: https://help.ubuntu.com/community/Vi...GuestAdditions which pretty much shows you exactly how to do it step-by-step.
As much as I would love to hold your hand and walk you through this, the best thing for you as of now is to consult the docs. We can still sing Kumbi ya though.
HTH
"Great understanding comes to those who find questions and question answers."