I used to have that game - its was GMT's 'Samurai'. It included Okehazama, Kawanakajima, Anegawa, Mikatagahara, Nagashino, and, of course, Sekigahara.
Here's a link to the site.
http://www.gmtgames.com/gbsa/gmtgbsa0.htm

I have no idea if its still in print or not. Its worth having, and a nice touch was commentary in the rules by Japanese historian Masahiro Yamazuki (who, among other things, points out that Nagashino may not have happened as we believe to have).