Error when trying to install yomikomu on Windows 7

[illtellyoulater]

Windows 7 64 bit:

ruby -v

ruby 2.3.0p0 (2015-12-25 revision 53290) [x64-mingw32]

gem install yomikomu

Fetching: mmapped_string-0.1.0.gem (100%)
Temporarily enhancing PATH to include DevKit...
Building native extensions. This could take a while...
ERROR: Error installing yomikomu:
ERROR: Failed to build gem native extension.

current directory: C:/dev/ruby/Ruby23-x64/lib/ruby/gems/2.3.0/gems/mmapped_string-0.1.0/ext/mmapped_string
C:/dev/ruby/Ruby23-x64/bin/ruby.exe -r ./siteconf20161111-9088-yryfnb.rb extconf.rb
creating Makefile

current directory: C:/dev/ruby/Ruby23-x64/lib/ruby/gems/2.3.0/gems/mmapped_string-0.1.0/ext/mmapped_string
make "DESTDIR=" clean

current directory: C:/dev/ruby/Ruby23-x64/lib/ruby/gems/2.3.0/gems/mmapped_string-0.1.0/ext/mmapped_string
make "DESTDIR="
generating mmapped_string-x64-mingw32.def
compiling mmapped_string.c
mmapped_string.c:1:22: fatal error: sys/mman.h: No such file or directory
compilation terminated.
make: *** [mmapped_string.o] Error 1

make failed, exit code 2

Gem files will remain installed in C:/dev/ruby/Ruby23-x64/lib/ruby/gems/2.3.0/gems/mmapped_string-0.1.0 for inspection.
Results logged to C:/dev/ruby/Ruby23-x64/lib/ruby/gems/2.3.0/extensions/x64-mingw32/2.3.0/mmapped_string-0.1.0/gem_make.out