Keep it in your C:\Windows\System32 (or better, in your PATH ). Run nkf --guess before you panic. And never let a stray byte spoil your data again.
For young developers in Japan, learning nkf.exe is still a rite of passage. It solves in one line what would take 100 lines of Python. nkf.exe
Power users combine flags for surgical precision. Keep it in your C:\Windows\System32 (or better, in