First off, topics similar to this have been posted in the "Help and Support" section, but i have yet to see it formally addressed with a working solution. (The repair option via installer did not help me)
At any rate just like subject title says, after launching onigiri.exe the launcher pops up and tries to update itself. However it seems to update itself in a break-neck pace only to end up withthe words "Update Failed. Please restart the game." apperaing on top of the update bar.
Any persons who had experienced this and managed to fix or even other possible solutions that may fix it, please feel free to post it.

Try restarting your computer and running Onigiri in Administrative mode. I restarted twice but I didn't patch first before I did XD. It is very important to run it in administrator though.

I've just tried your suggestion, but to no avail. Thanks for posting though.