http://www.pcgamer.com/niohs-pc-port-adds-mouse-and-keyboard-support-in-update-this-week/

A sloppy port mars Nioh's opening hours, said Tom earlier this month of Koei Tecmo and Team Ninja's latest ARPG. The one-time console-exclusive is now lining up an update which aims to address some of its issues on PC. 

I dived in for the first time last week, and, like Tom, was a wee bit disappointed with the Complete Edition's dodgy rendering and resolution settings. This update targets mouse and keyboard support, however, as well as key bindings and "other miscellaneous bugs" as outlined in this tweet: