After following the guide on the wiki, if the service is running, the client crashes instantly - sadly, no useful errors in the crash and all logs are in Japanese.
Where can I begin to try to sort this out?
I just found the extended troubleshooting:
Same crash with global injection and local install
Logs appear to have been created, but they are all empty. 
Hard to say, sadly, as I can barely find any details of that game online at all.
What you can test is to use the below base config that disables some of Special K’s various features.
Just download the file and rename it to whatever your SK config is called (so dxgi.ini, SpecialK.ini, etc) and overwrite your exiting config with this one.
sledgehammer.ini (341 Bytes)